Apertures and f/stops are not quite the same thing. An aperture is the size of the hole that the light passes through in order to expose the film. It is not complicated. f/stops are a set of standardized numbers used in mathematical formulas that are used to determine the size of the aperture. The "f" in f/stop is the focal length of the lens. Thus, if you have a 22mm lens, and you are shooting at f/2, then 22/2 = 11mm, which is the size of the aperture. If you are shooting at f/22, then 22/22 = 1mm, which will be the size of the aperture. Each progressive aperture, going from the largest number (let's say 22) to the smallest (let's say 2) admits twice the light into the camera that the preceding number does.
Shutter speeds are set up the same way. Starting from the fastest shutter speed (let's say 1/1000th second) and going to the slowest (let's say 30 seconds; but there really isn't a limit to how slow you can go -- some people with film cameras have used shutter speeds of a year or more), each progressive shutter speed admits twice the light into the camera as the preceding one.
Because they are set up this way, it allows you to use what are called "equivalent exposures." Let's say that your camera's meter is recommending an exposure of 1/125th second at f/11. Well, you decide that you want a little less depth of field than this. Depth of field is what the aperture controls and it is the amount of space in front of and behind the subject of the photo that will be in focus. To get less depth of field, you'd switch from f/11 to f/8; this admits twice as much light into the camera and without making an adjustment, your photo will be overexposed. To compensate for this, you switch from 1/125th second to 1/250th second, reducing the light by half (back to its previous level). Now you have an equivalent exposure that has the depth of field that you want. Simple.