Please help I don't understand the difference between work done by man and force applied by man along with everything else.

2. A man pushes a 10 kg box horizontally across a level floor at a constant speed of 2.0 m/s for 10 s. The coefficient of kinetic friction between the box and the floor is = 0.20 Find a. The force of friction fr = ung = 0.20 * 10 * 9 p = 19. 6N b. The force applied by the man = force of friction = 19.6N c. The work done by the man S X V( ) = 19 . 6 x 2 x10 = 392 1 d. The work done by the friction fox ( ut ) = 19.6 x 2x 10= 392 ) e. The change in kinetic energy of the box AV = 0 V SUK, E = O