Sheol means the grave, essentially. Everyone during OT times went to Sheol, meaning the grave. This is why there were different views of the afterlife among Israelites before Christ. Everyone went to Sheol, but on what Sheol was people disagreed. However, we can derive that Sheol is a waiting place, and does not mean we cease to exist, based on clues in the Bible. I'm phone posting so, look for then yourself, fam. Bible gateway, search for "Sheol, Hades, death, grave."
As mentioned before, there is speculation that "heaven" refers to a particular part of Sheol that's called Abraham's Bosom. This is a temporary dwelling place until Christ returns to defeat death, where Sheol will be emptied, and those souls judged, then it will be tossed to the fire.
Keep in mind that Hades = Sheol. Sheol is the Jewish word for it, Hades the Greek.
Emptied out:
Revelation 20:13:
>And the sea gave up the dead who were in it, Death and Hades gave up the dead who were in them, and they were judged, each one of them, according to what they had done.
Destroyed the following verse, Revelation 20:13:
>Then Death and Hades were thrown into the lake of fire. This is the second death, the lake of fire.
I am of the opinion of the above. That is, Sheol, divided into good and bad, is the temporary dwelling place before the coming of Christ in power to give us the eternal New Jerusalem.