This option will show the Error panel.
When there are no errors, the list will be empty. You will also be able to close the window.
When there are errors :
You will not be able to close the window until the error is solved and the program is checked/compiled.
The panel is dockable and by default docked to the bottom of the IDE.
When you right click the mouse inside the error panel, a menu will popup with one option : Copy to Clipboard. All data from the error window will be copied to the windows clipboard if you select this option.