I don't know why they keep it a secret until you've been in the program for a certain amount of time, I suppose they don't want to confuse you when you are still learning out basic points calculation.
I don't have the book on hand that explains it but from what I remember, it's basically the amount of points you would count if you don't really want to count points. For example, if you were at some kind of buffet and just wanted a lot of strawberries, you could eat all the strawberries you want and only count it as 2 points (as opposed to 1 point for 1.5 cups). It only applies to certain foods, I think things that are relatively healthy/filling foods. I guess it's just to take the stress out of eating in certain situations!