How do you say "She was pretty" in French? (grammar)

The way you originally wrote it is the passé composé, but one would rarely use the passé composé in this situation. That would translate to “She has been pretty”. You would more likely say “Elle etait jolie”, which is the imperfect tense.

Il á etait, or just il était?

“Elle etait…”

thorny is da homme to ask!

I suggest, “Elle était belle” is more about beauty. “Elle était jolie” would mean she was nice or pleasant.
I grew up in a French region and that was my mother’s first language.

I agree with “elle était jolie.”

@Dr_Lawrence While “belle” and “jolie” certainly do have different connotations, “jolie” still means “pretty” in most French dialects. Consider the song “Elle était si jolie,” for instance, which was translated into English as “She Was So Pretty.”