I’m guessing you’ve never heard of an appositive before. It’s not one of the first grammar topics you learn when starting to learn English. I bet you’ve seen them before but didn’t know they had a name. An appositive is basically a bit more information to add to an existing noun. This information renames or redefines the existing noun. An appositive is in the form of either a noun or a noun phrase.
Look at the example below, they all rename an animal by giving some extra information. The appositive is highlighted in blue.
An appositive can go at the beginning, middle or end of a sentence. It can also interrupt a sentence. Watch the video below to learn more about appositives and see some examples in use.