What is a use of return

Answer 1

Well, as the name suggests, it is used to return from a function ( it may or may not take a value with it depending on the return type of the function )

Answer 2

A function can return a value using the return statement.
Return stops the function's execution, and sends the value back to the calling code.

Check this post about Return statement:
https://www.sololearn.com/discuss/1226950/?ref=app
https://www.sololearn.com/discuss/2705345/?ref=app
https://www.sololearn.com/discuss/136121/?ref=app