Exposure and the basic camera functions
Exposure is the quantity of light that the camera admits to the image sensor. It is critical to get a proper image that is nor too dark or overly bright.
There are three main camera controls that control exposure. They are the lens aperture, with controls the amount of light admitted and also the depth of field in the photo, the shutter which sets the length of time that light is recorded that allows managing motion blur, and the ISO setting which acts like a camera sensitivity control – similar to a volume control – to make images brighter or darker.
Together these controls manage the exposure. They are often seen as the “exposure triangle”.
Here is an online video of a presentation on the exposure triangle that will give you a basic understanding of exposure, the aperture control, shutter speed, and the ISO control, and more.