Cards are used to create your Hero's decks, the cards have three stats, these are Strength (StrengthPvZH), Health (HeartPvZH), and Cost (SunPvZH/Brain). Some of the cards though will have unique special abilities which they can use in their favor in order to win against tougher opponents.
Basic Cards
Purchased at the store using coins that you have earned from battles.
Premium Cards
These cards can only be obtained at the store through Premium packs or by a free pack which you get when you lose a battle multiple times (usually 4).