Cultural emphasis is an important aspect of a culture which is often reflected though language and, more specifically, vocabulary. This means that the vocabulary people use in a culture indicates what is important to that group of people. If there are many words to describe a certain topic in a specific culture, then there is a good chance that that topic is considered important to that culture.
The idea of cultural emphasis is rooted form the work of Franz Boas, who is considered to be one of the founders of American Anthropology. Franz Boas developed and taught concepts such as cultural relativism and the "cultural unconscious", which allowed anthropologists who studied under him, like Edward Sapir and Ruth Benedict, to further study and develop ideas on language and culture.
One way in which cultural emphasis is exemplified is a populace talks about the weather. For example, in a place where it is cold and it snows a lot, a large collection of words to describe the snow would be expected.
In a place where it is hot, a cornucopia of associated terms would be expected.
A concentration of related terms for similar phenomena suggests the importance in distinguishing between them. Furthermore, if you are not from the area, or that culture, you might not have experienced or know the difference between, for example, a dry heat or a humid heat, when the difference may have huge implications for the outcome of a particular action.