Which words in the sentence are the appositive?
which words does the appositive rename?
the author charles dickens wrote some of the best-loved novels of all time.

Appositive is noun or noun phrase in which retitles, renames and helps describe the noun that is adjacent to it in the sentence. The appositive is like a more clear illustration or wants to illuminate the said subject in the statement. 
1.          The appositive word in the sentence is the author. Which describes and renames Gary Jackson in the sentence 
2.           It renames Charles Dickens.