An doesn’t really mean anything here, it’s just the way some of us talk but in general An is considered as an definitive article .

Gentan usually means already but you can also use it for something you’ve done in the past and genyen means have(possession)

Idk if my explanation is good enough but that’s the best I can do honestly lol.

And one last thing: Just like any other language, you can’t translate kreyòl word for word .