A mass m has weight W = mg, and that weight (which is normal to the horizontal) will have a friction force f = [itex]\mu[/itex]mg, where [itex]\mu[/itex] = coefficient of friction.
Now the external (applied) force at a angle can be resolved into horizontal and vertical forces.
When the horizontal applied force exceeds friction, the net force (Fnet causes the mass m to accelerate a.