Pretty much SnappleGirl explained it.
When you are more active your body can handle using more calories ie., points. For different activities dependent upon the intensity, your current weight and time you did the activity you earn points. These are optional and can be exchanged for food only on the day they are earned.
Meeting goers get this information in Week 3 however if you have e-tools ( the additionaly stuff from the online site) or are an online member it is available to you from the moment you start. For more information on e-tools or online see
www.weightwatchers.com and/or your meeting.