If a language learner is asked what they think the goal of a language course is, they would  probably answer that it is to teach the grammar and vocabulary of that language. But, if they are asked what their goal is as language learners, they  would most probably answer that it is to be able to communicate in that language.
I am not saying that in actuality the goal of a language course is to teach sololy grammar and vocabulary- well,  at least it shouldn't be just that anyone. Fortunately, the focus of second language teaching has moved from purely teaching grammar and vocabulary, to providing the skills for effective communication. In linguistics, a language course should not only have '' linguistic competence'' as its goal, but ''communicative competence'' in general.