How to setup keyboard to type other languages on Mac

Extract from https://support.apple.com/en-vn/guide/mac-help/mchlp1406/mac for reference:

1. On your Mac, choose Apple menu  > System Settings, then click Keyboard  in the sidebar. (You may need to scroll down.)
2. Go to Text Input, then click Edit. 
3. Click the plus sign (located at the end on left corner), then search for a language (such as Chinese, Simplified). Select one or more input sources for each language you want to use. 
4. Click Add.
5. To begin writing in another language, select the language you want to use in the Input menu in the menu bar.