Question

what is an apposition?

Answer 1

according to google,

ap·po·si·tion
ˌapəˈziSH(ə)n/
noun
1.
technical
the positioning of things or the condition of being side by side or close together.
2.
GRAMMAR
a relationship between two or more words or phrases in which the two units are grammatically parallel and have the same referent (e.g., my friend Sue ; the first US president, George Washington.

here's a article on appositions, http://www.grammar-monster.com/glossary/appositive_apposition.htm