Counters help you understand data better
You see the number of links, source pages, anchor texts, fragments, etc. at a glance.
This helps you get an immediate feeling of the volume of data you have in the current project.
Counters update with the Filter Slice
The benefit of seeing the data volume in your navigation extends to filter slices.
So if you filter by say "Only disavowed links" by clicking the preset tab 1 it applies trhe filter slice to the project 2
and the navigation updates all counters 3 to those affected by the filter selection.