How to Add Languages to Windows 10
Navigate to Windows Settings by clicking on the gear on the left side of the Start Menu. Click on “Time & Language”, then click on “Language” in the left sidebar. Under “Languages”, click “Add a language”. Find the language that you would like to add. Then click 'Next'. After that click “Install”. Using Alt + shift keys switch between languages.
How to Add Languages on Mobile Device
Tap Settings Tap General Management Tap Language and input Tap Add language and find the language to add Switch between languages