What does the numbers next to 'Backlog' / 'Active Sprints' / 'Reports' in a Scrum board mean?

[João Palharini]

When hovering over the afore-mentioned buttons on an Agile board, the numbers 1, 2 and 3 appear, respectively, between parenthesis next to the description of the button.

[João Palharini · Accepted solution]

These are actually shortcuts for accessing each view of the Scrum board. If you press any of these on your keyboard, the view will switch to the respective selection.