Shutter speed is the amount of time the sensor or film is exposed to light which creates the image, so yes it is important and necessary in order to make a picture.

Control over shutter speed allows you to get creative with the camera and your shots. In low light shooting the shutter will have to be open longer in order to get light to the film or sensor to make a legible image. In bright light the shutter will have to be faster so you don't overexpose the image which will cause it to become very light or "blow out".

You use shutter speed and aperature to control these effects on the shot.

Aperature is the measure of the amount of light allowed into the camera during the exposure. Think of it as a circle of black and the aperature is the size of the hole you cut into it in order to see through it.

Aperature will also allow you to shoot at faster shutter speeds or slower shutter speeds depending on what you have it set to or what the camera decides is needed (in auto modes).