One language on one website
Read this detailed guide how to use Loco Translate plugin provided with theme.
Multiple languages on one website
If you want to have multi-language website you need to use WPML plugin. Please note that you need to purchase 1 additional Regular theme license for our theme for every language on your site. For example if you have your site versions in English, German and Italian languages you need to purchase 2 additional regular theme licenses (in addition to current one that you have for English).
Check WPML Getting Started Guide for complete reference.