Most non speaking German ppl think there is only one German language. There are several dialects of German. From what we learned in middle and high school i think is low German, or is it high?
Standard High German (Hochdeutsch) is the kind taught in schools.
Of course, just like any European language there are tons of densely packed dialects that can be kind of difficult to understand (Swiss, Bavarian and Austrian all look like gibberish to me, not that I've got anything approaching fluency).
Low German dialects are spoken in northern Germany.