The Task Checklist is designed to give you a quick overview of any ads that require your attention:
The 3 bubbles under Tasks serve as your checklist:
The first bubble corresponds to the Review Ad Details drawer and indicates ads whose inventory, dates & prices are ready to review.
The second bubble corresponds to the Review Creative drawer and indicates ads ready for creative pre-approval or review.
The last bubble corresponds to the Submit Verification drawer and indicates ads ready for verification, or that require corrections to a previously submitted verification. The verification task will remain locked until the campaign start date.
Once you see the bubble with the checkmark, that task has been completed, and no further action is required.