The third major component of language is semantics, the meaning of words and sentences. Semantics rules allow us to use words to convey the subtlest nuances.
For instance, we are able to make the distinction between “The truck hit Laura” (which we would be likely to say if we had just seen the vehicle hitting Laura) and “Laura was hit by a truck” (which we would probably say if someone asked why Laura was missing class while she recuperated).