Hi. What File System means here is the way files are arranged in your computer. The computers have a way of arranging files in a systematic way so that they can be accessed very fast and easily, just like we arrange files in cabinet in a given order.
We have had a number of filling systems e.g. FAT 12, FAT 16, FAT 32, NTFS.
When you come to volume, or the volume label, it is the name you assign your drive. So, if you rename your drive to "Hubpages", then the drives volume will be appearing as "Hubpages". In your case, the hard disk has been given the name 'dirty'.