If your system is set to use timesheet approval, then you will submit your time rather than post it.
This means it can then get approved, queried, put on hold or rejected.
Queried and rejected are the only two actions that then require further input from you and they will appear at the bottom of your unsubmitted timesheets:
If you have a rejected timesheet the approver has to give a reason to reject them, so you can open it up and see the 'Approver's notes':
However, you cannot amend or resubmit a rejected timesheet. Your only option is to delete it.