Hades as used in the bible means the place of the dead, the grave pit. Hades is also used to indicate being spiritually dead, as used by Jesus in the
Lazarus and the rich man illustration. Hades means the same thing as
Sheol as far as the bible is concerned, only Sheol was Hebrew and Hades was Greek. See a Greek quote of a Hebrew scripture to prove this:
Psalm 16:10 - For You will not abandon me to Sheol; You will not allow Your Faithful One to see the Pit.
Acts
2:31 - He was not left in Hades, and His flesh did not experience decay.
In Greek mythology the meaning of Hades described more elaborately “the world of the dead.” These ideas about the place Hades represented in Greek mythology were eventually
grandfathered into the bible’s teachings regarding the place of the dead.
For some time around and after
325 C.E. when Rome was in the process of converting to Christianity, there was pressure for the church to cater their teachings to the beliefs of pagan nations in order to gain pagan converts. In consequence of these modified doctrines, much of what is taught among
Christendom today regarding the state of the dead was actually taken from Egyptian and Greek beliefs of these subjects.
Then
the sea gave up its dead, and Death and
Hades gave up their dead; all were
judged according to their works.
