There are a few ways to change the language in Joomla. The easiest way is to open the Language menu and select a different language.
Joomla also has a built-in translator that can be accessed by clicking the cog icon in the top right corner of the editor and selecting Translation. This will open a window where you can select the language you want to translate to and the language you want to translate from.
If you want to change the language of all the content on your website, you can use the Joomla Global Language Settings. To access this, go to the Extensions menu and select Global Language Settings.
This will open the Global Language Settings window. In this window, you can select the language you want to use for the website, as well as the language of all the content on the website.