The aperture is in charge of how much light can go through the leans, from your chosen size. It can be located in the leans and it works similar to your own iris. If you want more light in the photo, you set the aperture to a low number and get a larger hole. If you want less light in the photos, you set the aperture to a high number to get a smaller hole. So remember; The higher the number, the smaller the hole and less light in the photo.
Depth of field can be created through the aperture, it is when the focus of the camera is on one part of the photo while everywhere else is blurred. To create a shallow depth of field
(I know, I lied)