What do you know when we have knowledge of a language?

Question

What do you know when we have knowledge of a language?

would u help me to answer this question?

Answer 1

A standard answer used to be that to know a language one must know rules that allow the speaker to choose and combine elements of meaning from a finite repertory to yield a potentially infinite number of sentences.

Answer 2

This sounds like a test question, so I will only answer that one thing that we know is how to construct sentences with pronoun agreement.