In Crystallize, every tenant has a default language that represents the main (or perhaps only) language in which your catalogue content will be created. Multiple languages must be set up if you intend to offer your catalogue in more than one language. You can read more about configuring languages within the User Guide.
Once defined, languages create multiple “translations” of each product, document, and folder in your catalogue. You must supply your own content for each translation; Crystallize cannot translate one language into another. Also, please note that changes to the structure of one translation (e.g. adding/removing components) will carry through to the other translations.