Help is a function to request team members to send you Life. 
You can do this by tapping “Request” at the bottom right of the team screen.

With one request, you can receive up to 5 free Lives, or 8 if you have a season pass.

If a team member makes a Life request, you can respond to it by tapping “Help.”

Note:
You cannot make a Life request if you already have 11 or more free Lives or if you have made a request within the past 4 hours.