The theme is available in how many languages ?

The theme is available in English only.

How do I translate the theme to my language

The theme is translatable and we have included all the strings with the pot file. You can use a plugin like loco translate to translate the theme into your language. You can find instructions here :

Our only additional instruction would be to save the translations in “System” folder instead of “Author” folder.

Can I use this theme to build multi-lingual websites ?

By default WordPress does not support multi-lingual websites. However there are plugins like WPML, Polylang, Weglots, etc that allows you to extend WordPress to create multi-lingual websites. Please note that support for these plugins are outside of our support scope.