When two words, clauses, or phrases stand close together and share the same part of the sentence, they are in apposition and are called appositives.

In fact, an appositive is very much like a subject complement—without the linking verb:

Subject complement: My brother is a research associate.
Appositive: My brother the research associate works at a large polling firm.
Subject complement: Jean became a magistrate.
Appositive: I have never met Jean the magistrate.

Apposition