A good example I heard once was concerning the tagelharpa. It’s an Estonian instrument, historically used in Estonian culture, however if you hear it you’ll probably think Vikings. The modern viking/pagan/neofolk music scene uses it prominently, and as it has a much broader reach than Estonian culture, this has lead (through no fault of the musicians I must add) to situations where many people think of it as a “viking” instrument, even though it never was. Thus, a piece of Estonian culture is widely appreciated as belonging to another culture, due to popular media influence.

I don’t know if this is really an example of cultural appropriation, but that example helped me grasp the concept (if it is a good example).