のに connects two facts, A and B, which hold in spite of the expectation that if A is the case, B is not the case. "AのにB," therefore means "A, but contrary to expectations B, too" or "B, despite the fact A."
This company is rich, but it's workers' salaries are low.
The predicate in the part A is in the short form. When A ends with a な-adjective or with a noun+です, it appears as な, just like in teh exlanatory んです construction.
Ms. Tanaka is nice, but Ms. Yamada does not like her.