Formal:
* Une deuxième chance: This is the most literal translation and is generally the most formal option.
* Une nouvelle chance: This means "a new chance" and can be used in situations where someone is given a chance to start over.
Informal:
* Une autre chance: This means "another chance" and is a more informal way to say "second chance."
Idioms:
* Avoir une nouvelle vie: This means "to have a new life" and can be used to describe someone who is given a chance to start over.
* Redevenir quelqu'un: This means "to become someone again" and can be used to describe someone who is given a chance to redeem themselves.
The best way to say "second chance" in French will depend on the specific context and the level of formality you want to use.