Basically what it says on the tin. Script that changes filename and extension of the selected files, from one to many. Needless to say it but it's kind of useless if you have to rename just one file. It can be used to rename assets for web development, tv show episodes, lists of incoherently named same-type files.
For system administrators: make sure the bat is safe. As far as I can tell it can be launched only by administrators and changes to exec policy should be temporary, please do tell me if launching it causes security holes in the machine.