higher the number of f stop smaller the aperture ( yes the opening hole)
Smaller the aperture ( for example camera says F9) - more things will be in focus but at the same time the amount of light entering the camera is lesser so very bad focus (comparitively )
when bigger aperture (for instance camera says F1.8 or F3.2) bigger the hole that allows the light and hence much better and sharper focus but at the same time depth of field is lesser.
so if you want to take a picture of everyone in the room then it would be bigger f stop ( F9, translates to smaller aperture and lesser sharp picture), if you want to take a pic of one person in a room full of ppl then smaller f stop ( f1.8 translates to bigger aperture) and hence sharper picture.
Smaller F stops means more complicated and quality lens which is why a 50mm F1.4 is much more expensive than a 50mm F6 ( if one of that sort exists)
hope it helps