When used as a count noun, a “culture” is the set of customs, traditions, and values of a society or community, such as an ethnic group or nation. Culture is the set of knowledge acquired over time.
In this sense, multiculturalism values the peaceful coexistence and mutual respect between different cultures inhabiting the same planet. Sometimes “culture” is also used to describe specific practices within a subgroup of a society, a subculture (e.g. “bro culture”), or a counterculture.