Depends what you mean by explain it ...
Basically, if it became law, it would change the standard state-owned colleges and universities use in determining whether a student has violated campus policies against sexual assault/rape/etc.
The general concept, as I understand it, is this: it's a violation of the policy unless the person you're groping or boaning has manifested consent in some affirmative fashion. I assume that it doesn't have to be verbal, but can also include grabbing your penor or making shadow puppets of people boaning. But presumably the proponents of this would say that the idea is to change from an environment where the starting assumption is that you can do whatever you want to a woman unless she actively resists or expresses clear objection, to an environment where the starting assumption is that everyone's physical integrity (or whatever buzzword gets used here) is to be respected unless and until they clearly indicate they want to do the wild thing with you.
Question: What if she's drunk and claims sexual assault? Or what if the woman is vengeful and decides to put you through this form of legal hell? Then isn't that her word against yours? We already know that if either happens, the defendant will be guilty by the court of public opinion.
Are we eventually going to have to sign contracts of consent in order to avoid litigation and criminal prosecution? Because the concept itself isn't hard to understand at all..