This page displays the backup progress. Depending on the size of the data, and the performance of the server, the backup can take a widely variable amount of time. The top progress bar shows which table is being currently backed up, and how many rows have been completed. The bottom progress bar shows the progress on the database level – how many tables have been back up out of the total number of tables. 
If you cancel the backup while it is in progress, you will not have a complete and reliable backup, therefore it is not recommended to do that.