Hakred pretty much explained it all. I will add though that you can only trade in points for items if you live in the US, Canada or UK though. You can however trade in points for discounts off the official peta shop if you live outside of these though. You can earn as many as you like a day, it all depends how many actions you do ^_^
First of all – welcome to the street team! You earn points by taking action (http://www.peta2.com/actions/) on the street team. For easy access to street team missions, click the “TAKE ACTION” tab at the top of the page. Once you’ve accumulated enough points, you can trade them in for merchandise in the store (http://www.peta2.com/store/)! You can also navigate to the store through the link at the top of the page.