How does my camera work
The aperture is the hole in the lens that controls how much light gets through the lens to the chip.
The bigger the hole – the more light you get in.
The smaller the hole – the less light you get in.
A given lens will have a maximum aperture quoted on the body of the lens and a zoom lens will often have two different aperture numbers quoted.
A typical kit lens you get with your camera will typically have a maximum aperture around F4.5 or F5.6