Sealed Dragon Ball Wafer Cards
Every so often in Japan, they'll release consumables that have a free randomly inserted sticker or card in the back. In this case, Wafer Biscuits with a sealed Dragon Ball card.
There are many to collect in each series, of a few different rarities. Commons, Rares, SR's and GR's - SR and GR being the highest, respectively - and the most beautifully foiled and detailed. There are only a couple of these cards in each series.