Well its just showing you lots of info about your collection:
Missing Sets: 9 of 6507
means that you are missing 9 "sets" from the mame roms directory you just scanned. A Set being a whole game in a zip file.
Missing Roms: 664 (641 are 'nodumps') of 92971
This is a break down of the roms. Each game/set may contain hundreds of roms. Of the 92,971 roms in 6,507 games you are missing 664. BUT 641 of these are "no dumps" = do not exist. So in reality you are missing just 24 roms.
Note all the [0 fixed] stuff means that you ran the scan with various FIX tickboxes checked. I suggest doing this with caution (until you are confident) as it will change/rename/move/backup/delete your roms. Clrmamepro is great, but a wrong setup can cause havoc...!
Missing Samples: 35 of 2479
You are missing 35 samples.
Missing CHDs: 189 (26 are 'nodumps') of 189
You have no CHD's... in the rom directory you specified. A Lot of people keep CHD's in a seperate dir (you can add more than 1 rom dir in the setup section.)
Unneeded Files/Folders: 21
Literally means 21 files that are not recognised/misnamed. Ticking the "remove unneeded" options will remove these, but rename them if they are misnamed roms. If you have the Backup option set, it will store them in your backup folder too.
One last tip. under the "You prefer: Non-Merged Sets, Split Sets, Merged Sets" It is EXTREMELY important to select what matches your set.
I use Split sets (as do most torrents). If you selected something else, clrmamepro would busy itself duplicating everything which would take a loong time.