This window allows you to restrict the set of matching files by those which match the date interval specified.
The selection made in the above screenshot includes only files modified after 01/01/2000, but before the current date-time minus 7 days.
Relative dates are useful when you want set an offset back from the dynamic moments, like Now - the current moment, Last Backup Time - the moment the last successful backup (of any mode) was made, Last Full Backup Time - the moment the last successful Full backup was made.
Controls at this window:
Note: This option is enabled in the PRO version only.