When encountering a biblical word you don't understand, one method of discovering its meaning is to look up the word in a concordance and examine what the Bible says about it. A good example of this is Hades.

1. Examine this group of like verses. What do you observe about Hades?

And you, Capernaum, will you be exalted to heaven? You will be brought down to Hades! (Luke 10:15; Matt 11:23, NASB)

And I also say to you that you are Peter, and upon this rock I will build My church; and the gates of Hades will not overpower it. (Matt 16:18, NASB)

2. Examine this group of like verses. What do you observe about Hades?

And in Hades he lifted up his eyes, being in torment, and saw Abraham far away and Lazarus in his bosom. (Luke 16:23, NASB)

Because You will not forsake my soul to Hades, Nor give Your Holy One over to see corruption. (Acts 2:27, NASB)

he looked ahead and spoke of the resurrection of the Christ, that He was neither forsaken to Hades, nor did His flesh see corruption. (Acts 2:31, NASB)

Then I looked, and behold, a pale horse; and he who sits on it had the name Death, and Hades was following with him. Authority was given to them over a fourth of the earth, to kill with sword and with famine and with pestilence and by the wild beasts of the earth. (Rev 6:8, NASB)

3. Examine this group of like verses. What do you observe about Hades?

and the living One; and I was dead, and behold, I am alive forever and ever, and I have the keys of death and of Hades. (Rev 1:18, NASB)

And the sea gave up the dead which were in it, and death and Hades gave up the dead which were in them, and they were judged, every one of them according to their deeds. Then death and Hades were thrown into the lake of fire. This is the second death, the lake of fire. (Rev 20:13-14, NASB)