Did you post it with the question?
Appositive is defined as a noun, a noun phrase, or a noun clause which sits next to another noun to rename it or to describe it in another way. The sentence can still be completed without an appositive but adding it can present more information about the subject.
Here, maybe this link will help you answer your question:
http://www.ccthita.org/about/values/index.html
Hope I could help! Have a good day!
