I'm not professional, I'm just to share what I know. If my info correct you accept it, reject and comment if I am wrong.
What is Exposure?
Expose – Sure. It refers to amount of light falling on photosensitive material (film / CMOS sensor). We usually said what exposure I should have? Actually we are mention how much light I should let my sensor received and for how long?
What is Aperture
It is the most important things of a camera lens! It can be simple describe as a hole which allow light go through it. The larger the hole, the more light can go through it and vice versa. We can controlling the aperture of lens before we take photo, the wider the hole we open the faster the shutter return.
What is Shutter?
Shutter act with Aperture to control the amount of light fall on the sensor. The time for shutter open up is defined as shutter speed. It measure how fast the shutter opening and return. The longer the shutter opening or slower shutter speed the more light will allow enter to the sensor.
What is ISO?
It determines how sensitive of the sensor/film when expose to the light.