What is the relationship between language and social context?
There are many different approaches to this question, but one of the most obvious ways into thinking about the issues inherent here is to think about society and culture and how language relates to society and culture. You need to remember that really the language we speak determines so much of our world view or the way we look at and perceive the world. Consider for example that some desert tribes in the Sahara only have two words in their language for "flower". This is an indication of the way they look at the world as expressed through their language. On the other side, consider why Intuit tribes have a vast number of words for snow and its different states - far more than we do in the West. This again recognises the centrality of snow for them in their society. Therefore language has a very close and intimate relationship with society and expresses so much of our culture and the distinctive fashion we have of living.
To extend this discussion further to consider more precise social contexts, you might want to think about how language is expressed in various sub-cultures such as minority groups, youth culture (such as hip-hop) and groups of immigrants living in a different country. The same is true of these groups as they use language to fashion and identify themselves against other major groups.