A story map shows a sequence of steps users perform and alternative ways users can perform each step.
Cards on a storymap can become product backlog items in three different ways.
First, any one card on the map can turn directly into a product-backlog item.
If we're building an app or site that collects payments, for example, we may have a card that says, Pay with American Express Card.
That's a Product Backlog Item.
Second, because a column of cards represents different ways of doing something, the entire column can become one product backlog item.
If our map has a Column of different Ways to Pay, that Column can Become one big Product backlog Item.
Finally, a Sequence of Colums can Become one Big backlog Item.
On an e-commerce site, users can search, save items to a wishlist, check out more.
Wishlists will span multiple rows and columns.
it could become one large product backlog item.
This is a good idea if you won't develop that feature for a while.