The album is a section of the game in which you can view all your series of cards. To enter it, go to the game's Shop and then go to the Gems section, which can be found in the bar at the top of the screen.
Then click on "Get more cards" under the Prize Board and finally on "Album". You can also access by going to Menu > View Profile > Album.
There you can see the information of each card (prizes, rarity and description), add cards to your board and share them on your social networks.
The cards come in series of six units. As soon as you get the first 5 cards of each collection, you will unlock the Special Card. This will be the rarest card in the collection and the one with the best prizes.
We invite you to visit the article: What is the Prize Board? to be able to inform you about the use of your card collection in it.