Many reports include Filters, which allow you to limit the data shown according to certain parameters such as Locations, Roles or Employees.
Filters are shown at the top of the page.
To see what filter is represented by each icon, simply hover over the icon.
Click on the icon to open the filter. This will show a popup allowing you to specify which items appear in the report.
Simply click Apply to enable the filter.
To disable a filter, click on its icon, click Select All, then Apply.