At the top of each column, you'll see two different numbers. The first number is blue and the second is black in a white bubble as shown below.
The blue number represents how many total issues are in that column (card count).
The black number represents how many total points are in the column (size total).
The only time you won't see the black number is if there are no points assigned to issues in that column.
If you need a reminder, you can always hover over the numbers to show the popup.