You can add an input language, set a display language, or install a language pack in Settings to change the language that you use for Windows 10, apps, and websites. Adding an input language lets you set a language-preference order for websites and apps, as well as change your keyboard language.
The display language you select changes the default language used by Windows features like Settings and File Explorer.
If a language is listed under Preferred languages but doesn't appear on the Windows display language list, you'll first need to install its language pack (assuming it's available in your edition of Windows 10).
If you receive an "Only one language pack allowed" or "Your Windows license supports only one display language" message, this means you have a single language edition of Windows 10.