aperture is a setting. it tells how big the lens to open up to let in more light.

larger apertures will obviously let more light in so the image is brighter (OR u can shoot faster).

smaller apertures will let less light in, so u cant shoot as fast

this makes it desirable to buy a lens with large apertures so u can shoot faster for less blur

aperture is designated by the ratio f/x

a larger value of x means a smaller aperture as it's a ratio

a smaller value of x means it's a bigger aperture.

ie: f/2.8 >> f/5.6 (f/2.8 is bigger, and can shoot faster moving objects)