It's a bit complicated.
It's mainly french and french is the official language. French people there (except me, obviously
) are very obsessed by their language, so there's a bunch of laws about how everything must be at least bilingual and how you need to go at a french school except if your parents were english etc etc.
But there are also some english people who keep complaining about how everything is in french and about how the french think they're so better than them and stuff like that.
As you can see both sides kind of hate each other, so there are french quarters, english quarters and gay quarters.
=P