Perdition is mainly a religious concept from Christianity that means hell or eternal damnation. Perdition doesn't sound like a lot of fun.
If you hear someone say "the fires of perdition," they're talking about the fires of Hell. Perdition refers to hell, and especially the religious idea of eternal damnation: suffering for an endless period of time after death. You can also use this word for a more earthly kind of suffering. Just as people say "I'm in hell!" when they're unhappy, you could say someone in a bad situation is caught in perdition. When you see the word perdition, think "Suffering!"