Generally we use reports to view the data and print the necessary information.
There are cases wherein we will be required to export/print the report data into an Excel file and do a comparative study. Typical cases include reconcilation between GL vs AP or GL vs AR.
The below link will take you through on how to print any NAV report into an Excel sheet.
http://congruentdynamics.blogspot.in/2013/05/printing-reports-to-excel-in-dynamics_3.html