The friction force exerts a torque in the opposite direction to the torque that drives the wheel. During braking the tyre pushes forwards on the road surface, causing the road surface to push backwards on the tyre. The resultant force in the backwards direction causes the vehicle to decelerate. A deceleration is a negative acceleration.
Traction, or tractive force, is the force used to generate motion between a body and a tangential surface, through the use of dry friction, though the use of shear force of the surface is also commonly used.