It does tons of stuff. It's basically a component that the developer puts random features in that do cool things. For example:
- $calc() is like Panels UI's version of $eval() except it can do decimals also.
- $console(string) can write things to the console.
- $getimageinfo(file,mode) can provide you with the width / height or file type of the file provided.
- $files_ex(cmd,path,file) can get the size of all files in a folder(my suggestion to the developer

) and other things like the number of files in a folder.
- $textfile can read text documents
- $textwrite can write things to text files
- $setcontextmenu(name,'tf') can add functions with a one-click execution
It can also do loads of things with playlists

.
I have personally had a lot of problems with it and AVG Anti-virus (it isn't a virus tho) and it locks foobar up for me sometimes. The newest versions 0.2.5 and up seem to be okay so far however.