If you really want to get to grips with your camera then these basics will help. If you can study these you’re close to understanding all the basics!

Aperture is the hole in a lens through which light passes through to enter the camera and the sensor.
If you just think about how your eyes work.
As you move between bright and dark environments, the iris in your eyes either gets bigger or smaller.
In photography, the “pupil” of your lens is called aperture. You can shrink or enlarge the size of the aperture to allow more or less light to reach your camera sensor.
Aperture can add dimension to your photos by controlling depth of field. At one extreme, aperture gives you a blurred background with a beautiful shallow focus effect.
At the other, it will give you sharp photos from the nearby foreground to the distant horizon. On top of that, it also alters the exposure of your images by making them brighter or darker.
A small number such as 2.8 is actually a large aperture where lots of light comes through the lens.
A large number such as 22 is a small aperture and lets less light into the camera.
If you think about it as opposites it makes more sense !!
A large aperture is a small number and a small aperture is a high number.
A large aperture will isolate a subject and allow the background to go out of focus. Good for portraits.
A small aperture will bring everything into sharper view and works well with landscapes where you may wish to have the foreground and objects far away in focus.

Shutter speed exists because of camera shutter – which is a curtain in front of the camera sensor that stays closed until the camera fires.
When the camera fires, the shutter opens and fully exposes the camera sensor to the light that has passed through your lens. After the sensor has finished collecting the light, the shutter closes immediately, stopping the light from hitting the sensor.
Shutter speed is the length of time camera shutter is open, exposing light onto the camera sensor.
When you use a long shutter speed, you end up exposing your sensor for more time than if you used a quick shutter speed.
Shutter speeds are typically measured in fractions of a second, when they are under a second. For example 1/4 means a quarter of a second, while 1/250 means one two- hundred-and-fiftieth of a second .
Cameras can handle shutter speeds of up to 1/4000th of a second or sometimes greater depending on the camera.
Shutter Speed and Exposure
The other important effect of shutter speed is on exposure, which relates to the brightness of an image.
If you use a long shutter speed, your camera sensor gathers a lot of light.
By using a quick shutter speed, your camera sensor is only exposed to a small fraction of light.
Depending on your aperture and ISO configuration this can change the brightness of your image.

ISO refers to how sensitive the sensor in your camera is to light.
A high ISO makes the sensor more sensitive to light.
Raising your ISO has consequences.
A photo taken at high ISO will show more noise or grain in the image than one shot at a low ISO.
Every camera has a different range of ISO values.
ISO 100 (low ISO) ISO 200
ISO 400
ISO 800
ISO 1600
ISO 3200
ISO 6400 (high ISO)
When you double your ISO speed, you are doubling the brightness of the photo.
So, a photo at ISO 400 will be twice brighter than ISO 200, which will be twice brighter than ISO 100.
You should try to stick to a lower ISO if you can so you get the highest quality of image you can.
It is not always possible to do so, especially when working in low-light conditions.