The word "Sheol" occurs 64 times in the OT. It is always singular.
It is the realm of the dead, Proverbs 7:
Genesis 44:
It is below the ground, Numbers 16:
There is a fire at some deep level, Deuteronomy 32:
More hints in Psalms 49:
Jesus borrows the image of worms in the last verse of Isaiah 66:
In the NT, Jesus continues this progressive revelation of Sheol and develops the concept of hell, NIV Mark 9:
It is the realm of the dead, Proverbs 7:
Sheol is singular; chambers are plural.27 Her house is the way to Sheol, going down to the chambers of death.
Genesis 44:
It is a place of the dead.29 If you take this one also from me, and harm happens to him, you will bring down my gray hairs with sorrow to Sheol.
It is below the ground, Numbers 16:
At least symbolically, it is below ground.30 But if Yahweh make a new thing, and the ground open its mouth, and swallow them up, with all that appertain to them, and they go down alive into Sheol; then you shall understand that these men have despised Yahweh.
There is a fire at some deep level, Deuteronomy 32:
God can bring you down and up, 1 Samuel 2:22 For a fire is kindled by my anger, and it burns to the depths of Sheol, devours the earth and its increase, and sets on fire the foundations of the mountains.
Psalms 30 hints about the resurrection:6 "Yahweh kills, and makes alive. He brings down to Sheol, and brings up.
Souls are kept in Sheol.3 Yahweh, you have brought up my soul from Sheol. You have kept me alive, that I should not go down to the pit.
More hints in Psalms 49:
Psalms 86:15 God will redeem my soul from the power of Sheol, for he will receive me.
There are different levels in Sheol.13 For your loving kindness is great toward me. You have delivered my soul from the lowest Sheol.
Jesus borrows the image of worms in the last verse of Isaiah 66:
Hosea 13 alludes to the good news:24 “As they go forth, they will see the corpses of the men who have rebelled against Me; for their worm will never die, their fire will never be quenched, and they will be a horror to all mankind.
The OT does not clearly mention the concept of eternal conscious fiery torments for the wicket. It does hint at the good news of the resurrection of the dead.14 I will ransom them from the power of Sheol.
I will redeem them from death!
Death, where are your plagues?
Sheol, where is your destruction?
In the NT, Jesus continues this progressive revelation of Sheol and develops the concept of hell, NIV Mark 9:
See also47 And if your eye causes you to sin, tear it out. It is better for you to enter the kingdom of God with one eye than with two eyes to be thrown into hell, 48‘where their worm does not die and the fire is not quenched.’