The board view shows items as cards grouped by different criteria.
It is useful when you want to get overview how many items you have in each group, compare each group to the other or move items from one group to the other. You can also prioritize the items by dragging the cards around in the same group.
Typical example is the story board. It shows how many stories you have in each status – not started, in progress and done. And if you are close to your release date and you see that the “Not started” group has the most items, you’ll know you probably have problems.
Read more about setting up your boards: