This indicates that the pay period for the employee had been processed and payroll would not allow any additional changes to come through.
Your payroll team will need to untick the processed employee, after which you can then resend all the failed payroll submissions.
To resubmit a timesheet, follow these steps.
On a HR menu set, go to Timesheets.
Click Employee Timesheets (HR)
Find the employee.
Click the Approved tab, then select the timesheet.
On the right, click Resubmit.