The word “Hell” (or Hebrew “Sheol”) in the Old Testament Hebrew does mean “Grave” (or destruction).
Ecclesiastes 9:10, “Whatsoever thy hand findeth to do, do it with thy might; for there is no work, nor device, nor knowledge, nor wisdom, in the grave (Sheol), whither thou goest.”
This Old Testament scripture does support the Hebrew word grave or “Sheol” as the definition of Hell. In this case, Sheol is translated grave. But the same Hebrew word Sheol is used in Deuteronomy 32:22, “For a fire is kindled in mine anger, and shall burn unto the lowest hell, (Sheol) and shall consume the earth with her increase, and set on fire the foundations of the mountains.”
The translators used two different English words for the same Hebrew word. This scripture is speaking of a “Fire” which (much like a grave) is an instrument of active destruction. Items in a fire are consumed or destroyed.
The verses leading up to this one speak of the good times when the nation of Israel was in favor with God for obeying. But, future generations started falling away and began following other gods which makes Jehovah God angry, and he is going to actively destroy the blessings (destroy their increase) he has been bestowing on Israel because of their unfaithfulness.
The second part of your question asks “is Satan in a place of everlasting fire, or is he in the grave”? You are probably thinking of Revelation 20:10, “And the devil that deceived them was cast into the lake of fire and brimstone, where the beast and the false prophet are, and shall be tormented day and night for ever and ever.”
This seems to indicate that Satan is in everlasting fire. So, which is it? Is Satan in the Grave or Fire?
It is both. The Ecclesiastes verse is indicating a place of destruction. The Deuteronomy verse is indicating a place of destruction. Likewise, this “Fire” in Revelations is also a place of destruction. Revelations 20:14 proves the fire is symbolic because death and hell are also burned up. “And death and hell were cast into the lake of fire. This is the second death.” You can’t literally burn up death. Thus, the symbolic fire of Revelation foretells that Death and “Hell” (or the grave condition) will be destroyed forever.
We rejoice in the Revelation promise that in God’s kingdom, “…God shall wipe away all tears from their eyes; and there shall be no more death, neither sorrow, nor crying, neither shall there be any more pain: for the former things are passed away.” Revelation 21:4