What are those keys for and for what games?
http://us.battle.net/hearthstone/en/Hearthstone is Blizzard's latest game, it is a digital collectible card game. It will be free to play on release, but currently you can only play with a beta account.
If you are familiar with Magic: The Gathering, it's somewhat similar in basic concept. Simpler in most ways, streamlined to make online play fast and easy.