Sign language
From Wookieepedia, the Star Wars wiki.
Sign language was a language that used manual communication instead of or in conjunction with sound to convey meaning by simultaneously combining handshapes, orientation and movement of the hands, arms or body, and facial expressions to fluidly express a speaker's thoughts. In 17 ABY, there were 9,057 forms of sign language in the galaxy.
Examples of species that made use of a form of sign language include Polis Massans and Twi'leks.
