In your starter pack, there's a whole book on it
In short though, it's something designed to get you to exercise regularly on top of your usual daily routine (so if you always walk to work at a normal pace, that wouldn't count), and you get a certificate and sticker for your book once you've reached a certain level. So for bronze, it's 45 minutes of exercise per week, silver is an hour and a half, etc.
I'm personally going to get my bronze body magic award in my next session. All's that involves is 45 minutes extra moderate activity per week, so I've just been doing some brisk walks