Hi Scott,
You're welcome! We're glad to be of help!
Click on it and you can read the description in the bottom left. Basically, it allows you to change the language code (e.g. fr-FR) that is generated by Joomla. Here's an example that is also provided:
One has installed the fr-FR language pack and wants the Search Engines to recognize the page as aimed at French-speaking Canada. Add the tag 'fr-CA' to the corresponding field for 'fr-FR' to resolve this.
It's unlikely to work with FaLang though.
Kind regards,
Nick