Beginner, don’t be dismayed! It can be really easy to understand your camera and how the settings in the exposure triangle work the way they do. This explanation is the way I personally think of my camera as an eye:
The sensor in your camera is the brain. It receives data and information.
ISO is how sensitive the ‘eye’ is to the light. The higher the number, the more sensitive the eye.
Aperture is like the pupil. The wider it is (the lower the f/stop number), the more light is allowed into the eye. Over exposure is like when you’re inside where your pupils are more dilated to compensate for lower light. When you step outside, everything it too bright and your pupils have to get smaller to compensate for so much light. Then when you go back in, everything is too dark (under exposed) because your eye’s aperture needs a moment to open up and let in the light.
Shutter speed is like blinking. The faster it blinks, the less light is allowed in and vice versa.
As painfully simple as this is, it really doesn’t get too much more complicated than that – the explenations just do!
How about everyone else? If you had a total beginner ask you to explain how a camera works, what would you tell them?