R2-C4 or "Seefor" was a yellow R2-series astromech droid produced by Industrial Automaton that served the Royal Naboo Security Forces (source Wookieepedia.com).

He's part of the Rebellion somewhere between Dromund Kaas and Ves Vorshall, the Vertical City.

You can see him "teaching" some basic politeness to a MSE Droid.

You can watch him also on Youtube : https://www.youtube.com/watch?v=4HCA5kfY8Wk