Batch printing is printing all of the reports for a single project at one time.
Two batch print a report go to the test report button, and use the selection on the bottom half of the button to get the drop-down list as shown in the image below.
Once you select the batch print you will go through the standard print selection wizard. You will also be able to select which reports you wish to produce and in which order.
After this point, you will go through and select whether you want the report as a PDF or Excel workbook, which allows you to define the section on page numbering for each report.