Communication in both animals and humans consists of signals. Signals are sounds or gestures that have meaning to those using them.
Human communication consists of both signals and symbols. Symbols are sounds, gestures, material objects, or written words that have specific meaning to a group of people.
Key differences between human communication and that of other primates are that (1) humans have an open vocal system while other primates have a closed vocal system, and (2) humans have a larger bank of symbols to use in communication.