A wrapper is something which wraps around something else, making it easier to use. Here’s a definition: Wrapper Definition
In this case, I found Yarle had a ton of options that I didn’t really care about and took some effort to set up, so I instead wrote a shell script which automates those things. Since the shell script is for OS/X and UNIX systems, it won’t work on Windows unless you run a Linux VM or something.
For your case, since you already have Yarle installed, running it directly would probably be the overall path of least resistance.
– Doug