These cards are important and are used with Sony PlayStation devices to purchase games, programs, or even game add-ons, or what is known as DLC.
You can also use subscription cards to upgrade your account to a Sony PlayStation Plus account, which gives you the ability to play online, free monthly games, and other features.
Packing method: (after purchasing the card)
From the main menu of the playstation, go to the Playstation Store.
From the list scroll down to the Redeem Codes.
Now enter the code on the card in the designated field, and then click Continue.