What does exposure mean? How does the length of exposure affect it? How to control exposure?

If overexposed, the photo will become very white, if underexposed, the photo will be very dark.

Shutter speed, aperture index and ISO can control exposure.

The faster the shutter speed (1125 is faster than1100), the less light there is; On the contrary, the slower the shutter speed, the more light;

The larger the aperture index (F 1.8 is greater than F5.6), the more light enters. Conversely, the smaller the aperture index, the less light;

ISO stands for photosensitive speed. The greater the ISO, the faster the photosensitive speed and the more abundant the light. On the contrary, the smaller the ISO, the less light. However, if the ISO is too large, there will be noise.