Supported languages already have default translations for all texts used throughout your customer-facing store. However, any of these may be individually replaced as detailed here.
You can set your default language (and add additional languages for customers to choose from) in your store "General Settings", here: https://shoprocket.io/dashboard/settings/store#locales
If more than one language is included, this displays in the Store as a drop-down as shown, with default pre-selected:
