The deck builder is a feature that lets you create a custom set of cards that isn’t one of the typical series of card values.

For example, the traditional Planning Poker card decks use the modified Fibonacci values:
0, 0.5, 1, 2, 3, 5, 8, 13, 20, 40, 100

Other people use t-shirt sizes:
extra small, small, medium, …

When you create a game in planning poker, you can choose which series your team likes to estimate with. If you’re happy with the choices, then you don’t need to use the deck builder.

But if your team likes a different series of values, then you’d want to use the deck builder to make the cards they want.

For example, maybe your team wants values of fruit:
Apple, Orange, Pear, …

In the Deck Builder, the “Label” is the name that you see on the card. It’s limited to 3 characters, so you’d need to shorten your fruits like:
APL, ORG, PAR, …

The “Value” for the card isn’t displayed but is used in the averaging process. For example:
APL = 1
ORG = 2
PAR = 3

If one player chooses Apple, and another chooses Orange. If your settings are such that you have us automatically calculate the average, the average would be 1.5. And that rounds up to Orange. So in this situation, everyone picks their cards, we’ll calculate the average as Orange, and automatically assign the Orange card to this story (which you can edit or re-point if needed).