Here is a straightforward look at this topic for Malachain.
Exposure is the amount of light that reaches the camera sensor, and three settings control it. The aperture is the size of the opening in the lens; a wider opening lets in more light and blurs the background. The shutter speed sets how long the sensor is exposed; faster speeds freeze motion. ISO adjusts the sensor’s sensitivity, with higher values adding visible grain.
Changing one setting usually means adjusting another to keep the same brightness. A good way to learn is to use the semi-automatic modes: choose the aperture yourself and let the camera pick the shutter speed, then try the opposite. Take the same scene several times with different settings and compare the results to see how each choice changes the picture.
There is more to learn on this subject, and the linked website goes into greater depth. Treat this article as an introduction rather than the final word, and check any important decision against up-to-date, reliable sources before relying on it.
If you try any of these ideas, start small and adjust them to your own situation. What works for one person will not suit everyone, and it is fine to keep only the parts that help. Writing down what you changed, and what happened, makes it much easier to see after a few weeks whether the effort was worthwhile.
The most useful step is usually the first one. Pick a single suggestion, try it for a couple of weeks, and then decide whether it is worth keeping. Small, steady improvements last longer than ambitious plans that are hard to maintain once everyday life gets busy again.