This is the window that displays the Design Rule Check (DRC) results list.
You can toggle display of errors and warnings, and by clicking on the results list, the screen will move to the location where the problem exists allowing you to quickly resolve problems related to design rules.

By default, it is located at the bottom of the screen.
 

For more details about Run DRC, refer to Schematic Verification (ERC/DRC) and PCB Verification (DRC/MRC).

DRC Results Window Icon

If the Response Status changes from "Not yet" to "Approved", the Approver and Approval Date will automatically be registered in the Approver column.