If there's dysfunction, then things aren't working right. High blood pressure is a medical dysfunction, and fighting amongst teammates is a kind of social dysfunction.
If you know that function means to work, then you shouldn't be surprised that dysfunction means something isn't working. Blind people have an optical dysfunction. A family that yells all the time and never listens has a communication dysfunction. If your car breaks down, it has some kind of mechanical dysfunction. But if everything is going smoothly? You're dysfunction-free.