What is mean REV?

"REV" can stand for many things, so it's impossible to give a definitive answer without more context.

To help me understand what you mean, could you please provide more information? For example:

* Where did you see "REV"? Was it in a document, website, conversation, etc.?

* What is the context of the word? What is the topic being discussed or the document about?

* What do you think it might mean? Any guesses you have could be helpful.

Once I have more information, I can give you a more accurate and helpful answer.