Shutter Speed

Aperture is the amount of light let in through a hole. The wider the aperture the more light is let in so the picture has more exposure. The smaller the whole the less light is let in and the picture is dimmer. 

The shutter speed is the movement blur of an object. The faster the shutter speed the photo is fixed with no movement. The slower the shutter speed the photo will show movement of the focus object.

The ISO is the noise in the back of a photo. The higher the ISO is the more noise the photo will have. The smaller the ISO is the less noise the photo will have.