To dream of a foreign language represents a mindset that you don't understand. Feeling alienated, anxious, or helpless because you can't understand others. Difficulty understanding a new type of situation, social atmosphere, or business environment. Feeling that others are not making themselves clear to you. Someone may have an idea or belief system that you don't subscribe to. Feeling excluded or "apart" from something.
Negatively, a foreign language may reflect feelings about the culture of other people's friends and family that you don't like.
To dream of studying a foreign language represents your attempt to understand the behaviour of a person or situation that is currently unfamiliar to you. Learning to "speak someone else's language" in order to solve a problem.