ER model for barber shop
As far as a barber being connected to the appointment I'm with you guys on this. A foreign key [BarberID] in the appointments table links a barber to an appointment. The service being performed is also an attribute of that specific appointment. So the line from Performs should go to the appointment table. If anything, a foreign key relationship can exist between the barber table and the Services reference table, to create a list of services that a particular barber can perform (ex: not all barbers may be able to do highlights)

On a non-related note, I noticed that some of your tables are plural and some not. Try looking up some conventions for object naming and come up with something consistent, that would easily be followed by your future co-workers.