Maybe your baby cant speak yet, it can make alot of it needs clear to you with nonverbal language. Gestures are a form of communicating they know very well.
The average child start to speak its first words between the 13th and 18th month, but the communication starts alot earlier. Crying is a form of communication, but rubbing its eyes and sucking on its hands counts as communication as well. With a bit of experience you may tell what your baby is trying to make clear to you. Is it hungry or tired? The older a child gets, the more needs it gets. In stead of only communicating when its tired or hungry, it will try to make clear what kind of food it prefers or with what materials it wishes to play.