Once you have added languages here, you will find several translation tables that allow you to translate all static texts in the user interface, as well as dynamic texts from the product catalog, e.g. names of products, rate plans, features, charges, etc.
This table has an AUTO SAVE feature, so you'll never loose a translation :)
Use the dropdown to navigate between languages.
NOTE: you can use the translation table to override e.g. product and rate plan names coming from Zuora or other system strings simply by adding a translation in each language including the default language.