CBell-1 was an ancient code-based droid language. It was a binary language consisting of only two sounds the droids could make: one for yes and another for no.
Behind the scenes
The nature of only two sounds, in communication, which represents two signs or signals; yes and no, is the same as binary. Binary is a computer language consisting of two signs in combinations, analogous to yes and no, on and off. The Binary language in the real world uses logic; the logic code is between 0 and 1. In short, CBell-1 is a basic form of two-sign audible binary.