It's basically a little park, free to enter, dedicated to the World Cup; it's got a giant screen that shows every game, a large turfed area to camp out and watch, a little field to play against friends, and lots of vendors selling beer and snacks (although you are absolutely allowed to bring things in, which is probably a lot cheaper).
You can find all information about it's location and other details on the official website (in English), the link for which is above.