The Galactic droid lexicon was a language set up and derived for Droids when they were recognized as a species in 10,000 ABY due to advanced computer systems that allowed sentience and free thought.
The language was derived of Basic, Huttese, Bocce, countless trade languages, as well as the old binary droidspeak. It was designed as a new language that took over Binary, allowing other life forms to learn it and speak it, as few could decipher binary, and none could synthesize it. The droids were able to instantaneously pick up this language, of course, as it just needed to be added to their database, but it was not commonly spoken by other species.