PG Coins are special reward Coins that users can earn by taking certain actions on the website. PG Coins can be used to unlock special scratch cards that contain Steam keys. If you are a registered user, you can find the “Your account” link into the menu. Clicking on the link, you will be redirected to your main account’s page where you can manage PG Coins and other useful stuff. From that page you can also find more informations related to PG Coins and also request for a Coins conversion.
Remember that you also been will rewarded by unlocking some special badges. Visit the dedicated page to read more informations about the badges.