Timing alters the speed of a animation. The fewer the drawings, the faster the action and crisper the movement. Whereas more drawings between poses slow and smooth the action. Most animation is done in in twos (one drawing photographer on two frames of film) or on ones (one drawing photographed on each frame of film). Twos are used most of the time, and ones are used during camera moves such as trucks, pans and occasionally for subtle and quick dialogue animation.
Timing is also a factor in the acting of each character to develop things such as the mood, tone and even interactions with other character.
More frames at the end- slower movement as he comes to a stop.