As Jim said, RM&C is the Rename, Move, and Copy files tool. It's actually one of JRiver's best features, but it's sort of "hidden" because a lot of people don't know about it, or don't know what you can do with it.
RM&C can change your file names to be any format you want using the tags in MC's library. So you could name your files with track numbers and names. Or just names. Or just track numbers. Or the album and the name. Or any combination you can think of.
It can also move files around on disk you. If your files and folders are disorganized, you can use RM&C to move them around and impose a structure. This is done by selecting files and then telling RM&C what to do. It's not some sort of automatic, behind the scenes feature like Itunes AWFUL "keep library organized feature". It's a tool that users can employ when they want, using THEIR RULES on some (or all) of their files.
RM&C is also very useful when moving your collection from computer to computer. Or migrating files from one drive to another drive with a different drive letter. RM&C makes all of this fast and easy and preserves all of MC's information about your collection. There's essentially no reason to ever have to "re-import" all of your files in MC. Using RM&C you can bypass all of that and be back up and running in no time, with all of your import dates, play counts, etc intact.
I guess that's my pitch on RM&C for the day.
https://wiki.jriver.com/index.php/Rename,_Move,_and_Copy_FilesBrian.