What does caption mean?
You are correct!
From our dictionary:cap•tion
Pronunciation: (kap'shun), [key]
—n.
1. a title or explanation for a picture or illustration, esp. in a magazine.
2. a heading or title, as of a chapter, article, or page.
3. Motion Pictures, Television.the title of a scene, the text of a speech, etc., superimposed on the film and projected onto the screen.
4. Law.the heading of a legal document stating the time, place, etc., of execution or performance.
—v.t.
to supply a caption or captions for; entitle: to caption a photograph.