Sign language can be manual, that is, each hand symbol means one letter. Another type of sign language is the use of hand or arm movements to mean entire words. These are two types of communication for the deaf. Other examples are hearing aids, TDD (telecommunication device that can be used to type things over the phone) and even special closed caption for the television. Closed caption is a person who signs on television and this captioning can be turned on and off. Programs that offer closed captioning will advertise it when the program comes on.
Here are some websites that will be of interest: