Include subfolders: Check this box to include all subfolders of the selected folder when Scanning.
Clear Results before Scan: Check this box to cause the Scan Results to clear before making a new Scan, or uncheck to keep them so that you can build up a list of Results from separate folders.
Include files that do / don't have ID3v1 / ID3v2 Tag: These check boxes allow you to define which files are included or not included in a Scan so that you may choose which files you want to work with.
Scan Filter: Specify here the filter to use when scanning for MP3 files. You may use wildcards (? and *). Note: this takes precedence over any Scan Rules.
The Scan Filter takes precedence over any Scan Rules.
Scan Rules: Specify here Rules to use when Scanning in MP3's. This will filter only the MP3's you wish to work with by including or not including (as specified in the Rule) files that follow these Rules.
If you wish to find all the MP3's in your collection by the Spice Girls so that you can delete them, the following Rules would be apt for rooting them out using both the file name and ID3 Tag as the search keys:
Simulate Rules work in the order of the Rule numbers. So Rule 1 will be applied first... then Rule 2 will be applied on the result of Rule 1... etc.