How does changing the shutter speed change the look of the picture?
Depending on how slow the shutter speed is, you will see a change in motion blur. The subject has more time to move with a slower shutter than a fast one, so if you’re trying to freeze motion, use a fast shutter speed.
The shutter also affects the amount of light allowed to hit the sensor. With a faster shutter, there will be less light data captured. So a faster shutter is a darker image.