In addition to the languages customisation page you will also find that pages that relate to data that has language options will have a languages button.

The dropdown will display your supported languages for the online booking page. You can enable additional languages in Settings - Online - Languages: Choose your primary language using the top selector (default is English)

When you choose the selector the fields supported in multiple languages will glow gently in blue to show you what areas are open to translation.

For example this Category page, in inventory, lets you specify your product data in different languages:

You will only see this button appear on pages that relate to multi-lingual data. 

See Also

Languages overview

Language customisation