Change your server's language in System Preferences

If you wish to change your server's language, simply perform the following steps:

• Open the Apple menu and click "System Preferences"

• Click "Language and Region"

• Click the "+" button

• Choose your desired language and click "Add" 

• Confirm your decision on the popup

• Exit out of the window

• Say "No" to the restart prompt. Instead:
  • Log off server
  • Log back onto server

Here is an illustration of the entire process below:

Note: If you wish to change your keyboard's language, please see our relevant support article: Change Keyboard to non-English layout.

Sources

- macOS Sierra: Change the language your Mac uses by Apple