'Ben' in conversational Québecois is "bien", which means "well", "very" or "good" depending on the context.
Contrary to "bien" however, you do not pronounce the 'i' which is why you end up with "ben." If you speak French, it'd be pronounced "bin", and for you non-French speakers, worry not, "ben" in certain Québecois accents, is pronounced "Benne" which should be easy as it is the English pronounciation.
Luc: Comment ça va?
How are you?
Pascal: Ben...pas pire.
Ha ha! I meant to confuse you. In this context, "ben", contrary to your usual "très bien" response, means "well" in the reproof/surprise sense.
Sébastien: Je suis tout nu.
I am buck naked.
Mélanie: C'est ben p'tit!
It's so small!
In this context, it'd be in the "very" sense. So = very.
Jean-Carl: Ça va, bonhomme?
Are you alright, dude?
Jean-François: Ça va ben.
In this context, it's in the "good" sense; as an aknowledgement
I say "conversational" because this word arose from conversational Québecois, but there is no doubt that you will encounter this word in French books, poems or magazines.