Show mailbox total or unseen count
If you right-click any mailbox or label in the left sidebar, you can select Show total conversations count:
Showing the total count on your Inbox will help you better manage your Inbox. By archiving processed emails, you get a much better idea of what’s left to do. This is a good first step towards better email productivity and is inspired by the Inbox Zero method promoted by Merlin Mann and more recently by several other email apps.