Exposure means how light or dark the image you took with your camera will come out which is determined by the exposure triangle which contain 3 camera settings(aperture, iso, and shutter speed)
as aperture increases the f-stop values, the lens shuts. as it decreases the lens opens
light is a factor in the exposure of the photograph. aperture must be calibrated so the image will be clear and focused
I'm not sure on the last one but I know that when the aperture is low itll be a fast lens and when its higher itl be a slow lens I hope I helped :)
