Shutter Speed is when the shutter in a camera works when it is taking the shot. If you use a slow shutter speed the picture will be blurry and unclear but it shows how fast the object in the picture is moving. If you use a fast shutter speed the object in the picture will look still but its not showing if the object in the picture is moving.
Aperture is when the camera focuses on the object closest to the camera and blurs out the background. If you use a small aperture it will make both the object in the picture and the background and makes it really clear. If you use a bigger aperture the object in the picture will stay clear but the background will look blurred out.
ISO is the light in the camera. If you use Too much ISO it will look very bright and might have little tiny spots of colour. If you use less ISO it will look dark and you will not be able to see it very well.