"Tongues" I think can be interpeted either as languages, or as people (individuals who have tongues and are speaking)... I couldn't tell you the exact etymology, but effectively it means confused languages, or people who are speaking nonsense/can't be mutually understood.
A Google search for me also brings up a lot of Bible-related results, but I'm not aware of any translation that contains that exact phrase; I think it's mostly used for its poetic value, and the fact that it calls the story of Babel to mind.