What does the phrase Hell is other people mean?
It's a line from the play of Jean-Paul Sartre, Huis Clos(No Exit). In this play, several characters are left to sit in a waiting room that is meant to be understood as a waiting room at the entrance to hell. The characters think they're waiting their turns to enter and be tortured. But soon enough, through dialogue, the characters begin to torment one another, and it dawns on them that people can make each other suffer enough (just by the way they behave) that there's no need for any other hell.