Joomla! Certification Program™As a Joomla! administrator, you must know how to set up and maintain a multilingual Joomla! website inclduding, components, modules etc. Learn more about managing A Multilingual Website.
- Adding a new multilingual article.
- Updating an article in multiple languages.
- Adding a new multilingual menu item.
- Assigning templates, menu items and modules to a particular language.
- Language overrides
- For any newly added components, modules, etc
- Changing the Administrator language settings
- Setting a different frontend and backend language
https://docs.joomla.org/J3.x:Setup_a_Multilingual_Site/Enabling_the_Language_Plugins