ISO - If the number is low the light would be more sensitive.
SHUTTER SPEED - how fast it opens the photo would be dark and the slower it opens it would let more light in.
APERTURE - larger the aperture the more blear gets in and the narrower the aperture it would be more in focus and the depth of field would be more lighter
These two photos are when the shutter speed is high.
These two photos are when the shutter speed is low.