Originally Posted by Reel
The guy who created the Avatar language created the Kryptonian language for the film. It will probobly be spoken in Krypton flashback sequences.
Zod speaks it Superman when they first meet and then speaks English saying "Do you know your native tongue Kal-El?" So it is clear that Kryptonian's know both languages..
He said "Do you know your native tongue Kal-El?" in Kryptonian then superman responded in english, Who are you.