You can open this dialog with the menu item "Report | Document Properties ...". The Summary Info allows you to place additional information or comments in the report. Insert special fields from the field browser in order to insert this information.
Author - here you can enter the name of the author
Keywords - here you can enter keywords which specify what your report is about
Comments - here you can enter additional comments which probably describe what your report shows
Title - here you can give your report a title (which will also be displayed in the title bar of your report window
Subject - here you can enter a subject for you report
Template - here you can enter the name of a template which has bend used to create the report
Created - Date on that the report has been created
Last Saved - Date on that the report has been saved last time