What does -An ye harm none do as ye will- mean?

I believe it means that if you are going to do spells or magic of any sort, that you do not use them to try and hurt anyone, or go against their free will. It also means to live your life how you want, but don't hurt anyone.

The Wiccan Reade "An ye harm none, do as thou will" has many interpretations.

At one end of the scale, some say - as long as your intent is "good" you can do anything you want. At the other end of the scale are those who believe you shouldn't do anything that could in any way harm and living thing. (this includes becoming vegetarian and many other life style choices)

I believe the important thing here is define the Words "harm" and "none" as being the pivotal part of the concept.