There are 2 sets of rules, actually.
There's the Terms of Service
that you agreed to upon signing up
And the Community Rules
Both are enforced here at AA.
This is an english speaking forum, as annotated in the Community Rules
The language of this forum is English. If you are not a native English speaker, do your best. We are glad to have you as a member and will be supportive and polite.
As Steve mentioned, both links I've provided in this post are always available in the bottom toolbar of everypage, just scroll way down to the bottom and you'll find it.
Hope that helps!