This python module provides an API with data about languages/regions/scripts for use in the language-support categorization of the font families in the Google Fonts collection.
You can also directly access the raw textproto files on the Lib/gflanguages/data directory:
Most of the code in this project was copied from the gftools repository (https://github.com/googlefonts/gftools/) so that language/region/script data can be easily available to all our tools without having to also get the large dependency tree of gftools. The most immediate user of this module is Font Bakery, which needs to validate language support on font binaries being checked. (see fonttools/fontbakery#3605)
The second obvious user of this gflanguages module is gftools itself.
Language/region/script definitions and the gflanguages modules are used as a subtree in the google/fonts repo, on its lang/ directory (https://github.com/google/fonts/tree/main/lang).
This module is the main place to update these definitions, avoiding data duplication and guaranteeing uniformity across tools.
To learn more about how lang metadata affects downstream, see gf-guide/lang.