Summary: The GSA has a number of available language bundles that can be used for spelling suggestion and query expansion. Google provides a default, pre-installed, language bundle for English, Portuguese, French, Italian, German, Spanish, and Dutch. To download other bundles and install them on your GSA, see How do Language Bundles Work?
Additional Information: Language bundles include basic data for spelling suggestions and query expansion. It is also possible to provide additional query expansion terms by uploading a file to the GSA in the Admin Console under Serving > Query Settings.