Hand sign

Manual communication systems use articulation of the hands (hand signs, gestures) to mediate a message between persons. Being expressed manually, they are received visually, and sometimes tactually (see tactile signing). Manual communication, when it is a primary form of communication, may be enhanced by body language and facial expressions and other forms of communication.

Manual communication is employed in sign languages and in systems that are codes for oral languages (see Manually Coded Language).

Other, simpler forms of manual communication have also been developed. They are neither natural languages nor even a code that can fully render one. They communicate with a very limited set of signals about an even smaller set of topics and have been developed for situations where speech is not practical or permitted, or secrecy is desired.

...
Wikipedia