Universal Alien Language is a set of symbols similar to letters, used particularly by many alien species in the Milky Way and Andromeda.
These set of symbols have been seen in various episodes as Ben 10,000, Grudge Match, Ben 10: Race Against Time, Inferno, Vreedle Vreedle, and Basic Training. Unlike the Sotoragg language, this language almost reads the same in English, because Gwen was able to read it without problems.
No official source, such as Man of Action has given a specific translation to any of the symbols.
Universal Translators can be used to understand the language for aliens who haven't learnt it.