What is Sheol (Hades/grave/hell)?

Beware of false hellfire doctrines!

False hellfire doctrines are warned to all:
Luke 9:55-56 “But He turned and rebuked them, [and said, “You do not know what kind of spirit you are of; for the Son of Man did not come to destroy men's lives, but to save them.]...”; Luke 13:2-5 "And Yahushua said to them, Do you suppose that these Galileans were greater sinners than all other Galileans because they suffered this fate?  I tell you, no, but unless you repent, you will all likewise perish.  Or do you suppose that those eighteen on whom the tower in Siloam fell and killed them were worse culprits than all the men who live in Jerusalem?  I tell you, no, but unless you repent, you will all likewise perish."; John 12:47 “If anyone hears My sayings and does not keep them, I do not judge him; for I did not come to judge the world, but to save the world.”; Matt. 6:30 "But if Elohim so clothes the grass of the field, which is alive today and tomorrow is thrown into the furnace, will He not much more clothe you? You of little faith!"; Luke 3:6 "And all flesh will see the salvation of Elohim."  

On the contrary to those hellfire doctrines, 
the Son of Man does not come to destroy men's lives, 
but to save them by their repentance

As to those hellfire false preachers, why would He destroy us if He knows us before we are created in His image?  Beware of those who preach the hellfire teachings to many that are the judges of their (unrepentant) evil deeds.  Yahushua our Messiah comes for all to repent for one reason that He does not come to destroy or judge the world (His people), but to save the world (repentant ones) because He died once for all sins of this world.  Hos. 1:9-10 “And YHWH said, Name him Lo-ammi, for you are not My people and I am not your El.  Yet the number of the sons of Yisrael will be like the sand of the sea, which cannot be measured or numbered; And in the place where it is said to them, You are not My people, It will be said to them, You are the sons of the living Elohim.”; Luke 3:6 "and all flesh will see the salvation of Elohim." 

Luke 5:32 "I have not come to call the righteous but sinners to repentance."
The rich man in the Sheol is spoken not only to his brothers but to all mortals who are commanded to repent from the kingdom of lawlessness by keeping the commandments of YHWH
Being the worldly rich man cannot carry his mortal things that 
belong to the kingdom of corruption, to the Kingdom of incorruption/
immortality, therefore he has to throw his mortal/lawless works in
Sheol thru his repentance that is only the point of reversal/turning
 around to the Kingdom of Life from the kingdom of death so he has to build his spiritual values in which YHWH is more interested to receive the spiritual production into His dwelling of eternity.
That is why the rich man gave the warning to his brothers to repent and to obey the Law of Life. (Luke 16:27-31)

YHWH has created us in His image because He loves us and He is not willing to perish any of His people, but to command us to repent wholly from the kingdom of darkness eventually to His Kingdom of Light.  He is a good Father to fight all the way to win all the hearts of His beloved children!  Luke 16:19-31: Even the rich man wanted to send his message to his brothers about the repentance out of the kingdom of lawlessness and their obedience to the Mosaic Law of His Kingdom of Life, as it is not a literal eternal hellfire, but it is figurative to perceive that all must repent from doing the evil deeds, just like the rich man acknowledged his deeds of evilness.  All who have not repented are in the place of torment (Shoel/Hades) until they repent completely to enter His Kingdom of Life.  We, the believers, share His sufferings during the shortened days in the persecution of the lawless (unrepentant) ones (2 Peter 2:7-9).  His consuming fire upon this world (Luke 12:49) is to purge all the works of evilness out of our hearts to be His true people at the ends of our fleshly ages.  YHWH is full of mercy to all mortals to come to their true repentance.  Everyone that has a knowledge of good and evil, in creating the deeds of opposition must repent out of the kingdom of darkness by throwing out the dark (fleshly) things and do good things out of His Law of Life in His Kingdom of Light.  Acts 26:18 “to open their eyes so that they may turn from darkness to light and from the dominion of Satan to Elohim, that they may receive forgiveness of sins and an inheritance among those who have been sanctified by faith in Me.”  

Matt. 5:19 “Whoever then annuls one of the least of these commandments, and teaches others to do the same, shall be called least in the kingdom of heaven; but whoever keeps and teaches them, he shall be called great in the kingdom of heaven.”; 1 Cor. 15:22 "For as in Adam all die, so also in haMashiyach all will be made alive."  All are drawn up Himself at the ends of their mortal ages (John 12:32) where all are measured of their spiritual values.  Those, who are least in the Kingdom of heaven experience their works of foolishness in the world of mortality, repent for their spiritual values that were lost and are now restored (found) by their obedience to His Law of Life because they are awakened in the Day of judgment acknowledging of their evil deeds in the previous lives. (Matt. 11:21-24)  All begin with the works of foolishness (darkness) and end with the works of wisdom (Light) joyfully!  What are perished must be the works of lawlessness opposed to His Law of Life.  For everyone that has the knowledge of good and evil, creating the deeds of opposition, only his deeds (spirits) of foolishness are perished and his deeds of wisdom thru His Spirit are saved!  1 Cor. 3:13-16 "each man's work will become evident; for the day (of salvation/judgment) will show it because it is to be revealed with fire, and the fire itself will test the quality of each man's work.  If any man's work which he has built on it remains, he will receive a reward.  If any man's work is burned up, he will suffer loss; but he himself will be saved, yet so as through fire.  Do you not know that you are a temple of Elohim and that the Spirit of Elohim dwells in you?
John 3:5-8 “Yahushua answered, "Truly, truly, I say to you, unless one is born of water and the Spirit he cannot enter into the kingdom of Elohim.  That which is born of the flesh is flesh, and that which is born of the Spirit is spirit.  Do not be amazed that I said to you, You must be born again.  The wind blows where it wishes and you hear the sound of it, but do not know where it comes from and where it is going; so is everyone who is born of the Spirit.”; 30 “He must increase, but I must decrease.”, therefore every perishable (fleshly) deed of lawlessness must go to the kingdom of death, and every imperishable (spiritual) deed of His Law must go the Kingdom of Life.  All are commanded to repent from the kingdom of darkness.  Rom. 14:11 “For it is written, “As I live, says YHWH, Every knee shall bow to Me, and every tongue shall give praise Elohim.” (Phil. 2:10-11)   Be perfect as He is perfect!  HalleluYah!'''

Where are they now since they were perished in the Flood of Noach?
The spirits in prison (Sheol) who once were disobedient 
in the days of Noach, during the construction of the ark,
 to His Kingdom of Life upon their repentancenow freedare 
so all disobedient ones today are in the prison of lawlessness 
till their repentance out of Sheol 
From the complete study to perceive spiritually with all His compassion on all repentant ones upon the
verses of 1 Peter 3:18-20, it gives us all to perceive spiritually that Our El is not willing to perish all 
unrepentant ones but to save all that must repent from the kingdom of wickedness.
Only the works of corruption must be perished at the end of the fleshly age.

What is Sheol (Hades/Gehenna/grave/hell)?  "You will be brought down to Sheol" and "to destroy both soul and body in Sheol" is acknowledged for the unrepentant/disobedient one who refuses to repent from the kingdom of darkness even till or after his death, then the day of judgment opens his eyes to perceive his works of lawlessness against His Law of Life.  Only the miracles to turn to His Kingdom of Life (Light) is to repent wholly from the kingdom of death (darkness).