Replace Open Sans with a local copy to speed up admin testing and development.
Local Open Sans contains copies of Open Sans fonts that WordPress loads from Google Fonts. The plugin deregisters the admin style that loads these fonts remotely and replaces it with a stylesheet that loads local copies of the same fonts.
Recommended for development when "fonts.googleapis.com" is adding time to admin pageloads. Not recommended for production (live sites) because it is almost always faster for your visitors to load fonts from Google or to use cached copies.