When you have earned 1000 points you can receive a Google play gift card! If you've set it as your goal, you can just click on the goal bar on the top right corner and claim one instantly. If you haven't set it as a goal, click on Gift Cards Store on the side of the homepage under Redeem Points. Here you can view the site's available prizes. In the search bar enter "google" and search. The Google Play logo should come up, go ahead and click redeem then select the amount which you wish to obtain.
What else is there?
You can get way more than just Google play cards. There are other options in the gift cards store, including but not limited to: