Your camera's shutter speed is basically the speed at which the camera opens the shutter and lets the light fall on the sensor to record the picture. Shutter speeds come in various incremental steps, measured in seconds. Shutter speed is important to your photographs as the quicker the shutter speed, the sharper the image will be.

High shutter speeds are great for taking a snap of something fast-moving, because it's only looking at the fast-moving thing for a very short amount of time.  Low shutter speed will give a great motion-blur effect, because the camera's looking at all the things that are going on for a long time.