Revision is rereading your writing and changing major parts of it, not just mechanics. If something does not make sense, you change everything that you need, not just one sentence. It is like turning coal to diamond, crummy to great (even though that is not possible.)

I really like my Arabian Nights Story. I had a very good plot and story line, but I did not spend enough time on it. If I could rewrite it I would spend more time on it. When I revised my piece, I made the story about the wolf a real story, not just a sentence recapping it.