Installing Joomla Language Pack
Installing a language on your Joomla site is quite easy. Firstly, navigate to Extensions > Languages section. In the Languages: Installed (Site) section, click on Install Languages button located at the top left of the page.
On Extension: Install Languages page, you will see the list of available languages for you to install. To refresh the list, click on Find Languages button and the list will get updated.
Search and locate the preferred language. Click on the checkbox of your preferred language and click on the Install button. A message will be appeared and your language will be automatically installed.
Enabling Preferred Language
To enable your preferred language, navigate to Extensions > Languages > Installed section as shown in the following screenshot. Click on the Star button to set the selected language as your site's main language.