IFRS is Input File Repository.
Below title field you will see 'File Name' field. It shows actual source location i.e physical file location in your server's file system.
Default path for 'Input' folder is "<instastallation_directory>/SAP BusinessObjects Enterprise XI 4.0\FileStore\Input"
e.g
C:\Program Files (x86)\SAP BusinessObjects\SAP BusinessObjects Enterprise XI 4.0\FileStore\Input