They can churn, check, channelize. They can forge a fiery army out of a hundred languid men. One way to look at language is to consider the forms, the meanings and the circumstances involved in any given utterance. The traditional role of speech in the society, the social roles of the participants, the social setting, etc. This linguistic knowledge is referred to as competence .
Competence refers to a person's cognitive ability to acquire language.
For further study about language Chomsky, Noam. Language and mind. 2nd edition, revised. Lenneberg, Eric H. 1978. Edited by George A. Miller and Elizabeth Lenneberg.