If a wide receiver is in route to catch the football, jumps and hits a referee and it interferes with the completion of the football. What happens?
The play counts as any other failed play would and the offense resumes with the next down.
What is the name for a call like that? And does anything happen to the referee for it?
The play is called "an incomplete pass". Its no different than a pass where the ball hits the goal post and bounces off without being caught.
What would you expect to happen to the referee? Hopefully, he isn't injured in all of it and play goes on. The referee on the field is an accepted hazard of the game and it is the responsibility of the player to avoid running into them.