Force is given by the product of mass and acceleration. A force applied to an object results in a change in its velocity.
Here, the initial velocity of the puck is 0 m/s. When the hockey player strikes the puck and exerts a force on it the velocity increases to 50 m/s in 0.0121 seconds.
The acceleration of the puck is (50 - 0)/0.0121 = 4132.23 m/s^2. The force that has been applied and which results in this is the product 0.167*4132.23 = 690 N.
A force of 690 N applied for 0.0121 seconds increases the velocity of a puck of mass 0.167 kg from rest to 50 m/s.