It is very important to submit the timesheet so your progress can be tracked for its financial impact to the project.
For normal user, you can access the Timesheet from your side bar under the Project module.
You will see two buttons right from your Timesheet display; New Entry and Submit Week for Approval. But if you have Project Manager role or Administrator role, you will be able to see an additional button named Pending Approval.
Creating Daily/Weekly Timesheet
Submit Week for Approval
Once you have recorded all your timesheet for a week, either through Daily Timesheet or Weekly timesheet, you need to submit the timesheet for approval.
Typically the Project Manager will review this and he/she will decide to approve or to reject the timesheet.
The approved timesheet will be calculated for its billable rate in Project.
Pending Approval button is for PM / Administrator role user to access to the Timesheet list of approval request. You can either approve or reject the request from this page.