During editing, the recorded material is tuned and time corrected to varying degrees to make your material more pristine. As I mentioned in our tracking article, it's really important to get as good a recording as possible during tracking so that you don't have to edit as much. You will need to edit some though and I definitely recommend hiring someone with large amounts of experience to do this step for you.
An editor (sometimes the producer who tracked you, a separate editor, or perhaps someone from your group who wants to learn how), imports your tracks into editing software like Melodyne and spends 1, 2, 3, 4, 5 or more hours cleaning everything up so that it all fits together and is in tune.
Editing is not a cookie-cutter formulaic process. Each recording is different and needs different treatment. Music is diverse and an editor needs to be a good musician that can make choices based on the music that they are editing. It's very easy to over edit and finding someone with experience can make all the difference in getting a great edit that doesn't sound like you were edited.