What do you think the author means by the statement, "a prop is worth a thousand words"?

I think it means that it speaks loudly in a silent sense. For example props in a play or stage say something about the time/age, when and where, or give hints to what its about. Let's say there is a boat on a stage, you can concern that the play involves a boat or most likely water. Hope this helped, if you want more just ask.