Hi Detonator, at first it may all seem confusing but it'll soon become second nature.
The 24-120mm means it's a zoom lens with focal lengths between 24 and 120mm. This means the lens will have a ring on it which you can turn to change the focal length between 24 and 120mm. 24 being wide angle(ish) and 120mm being telephoto. So this lens can be changed from somewhat wideangle to (somewhat) telephoto. This would be a pretty standard lens to take on a holiday trip or something so you can make photos of a wide array of subjects. This lens is actually quite a nice lens.
Now macro is something completely seperate. Im sure there are lots of descriptions, but to me macro means you can get 'life size' pictures and 'larger than life size'. This means that if you take a picture of the subject, you would see it just as large on your film, as it would be in real life. Basically you are filling the frame with the whole subject. This is also denoted as 1:1. You can also do large than life, basically blowing up a subject so it fills your frame. Something that would be half the size of your film, say a blenny, would be blown up to fill the whole film, showing immense detail.
In digital photography this doesnt quite hold up, but the same principal applies. To make macro photos your lens needs to be macro-capable. The 60mm Nikkor lens is one, so is the 105mm and the 200mm. They are generally accepted as the best macro choices.
Do know that when you shoot digital, the focal length will actually NOT be the same as what your lens says. There is a multiplication factor. For my D100 it's about 1.5x. This means my 12-24 mm lens will actually behave like an 18-36mm lens _on my D100. If i'd put the exact same lens on an F100 film camera it would be 12-24. This has to do with CCD chips and bla bla..not important, just remember it.
f/3.5-5.6 is indeed the aperture. The smaller the number, the larger the opening in the front of the lens, the more light will be let into the lens. Aperture is measured in f-stops. So f8, or f2.8 are f-stops. It's sortof like the pupil of an eye. The more light you can let into the lens, the shorter you have to open the lens to let a certain amount of light in. This means the lower your f-stops can go (towards 2.8 or even 1.2), the less light you need to properly expose your subject, so you can work in dimmer environments. The f stop also controls how much of the subject is in focus. The smaller the aperture (higher number, say f22), typically the larger the depth of field will be. This means more of your subject will be in focus. Properly exposing a subject means finding a balance between f stop and shutter speed (amongst other things).
When they tell you the f-stop on a lens description it usually means the lowest f stop possible. For zoom lenses this is usually 2 numbers, because the largest aperture (smallest number) changes at different zoom lengths. So, f/3.5-5.6 means the lens can go down to 3.5 at wide angles, and 5.6 at telephoto range. 5.6 is actually not so good, BUT the VR capability makes up for a lot of it. It means you can use slower shutter speeds to make up for the smaller amount of light you can let in.
G means the lens doesnt have an aperture ring, and if you want to change aperture you need to do it on the camera body itself through whatever dial there is that changes the f stop. This is a relatively new addition to Nikon lenses.
ED-IF stands for "Extra low Dispersion, Internal Focussing". ED counteracts Chromatic Aberration which, simply put, is some form of distortion you get with certain lenses. IF means the lens focusses internally, which means it wont get any longer than what you see. If you twist the focus ring you'll only see it move inside the lens.
AF-S indeed stands for Auto Focus, Silent wave. This means the lens is a very fast focussing quiet lens. Handy when you want to shoot skittish wildlife that might not like the sound of a focussing lens 
VR is Vibration Reduction. It allows for hand-held shooting at slow shutter speeds. It basically counteracts your hand shaking slightly and thus giving you a sharp picture where otherwise your hand shaking would have made the picture look crappy.
Zoom doesnt mean Telephoto. It means you can change the focal distance, in this case between 24 and 120mm. Telephoto just means a certain range of focal distances. Id say anything above 70mm is Telephoto. So a 600mm lens is a telephoto, but not a zoom. And a 24-120 is both telephoto capable and zoom.
Nikon is obviously a company name. Just like Canon and Leica are company names. Actually, Nikon is called Nippon Kogaku K.K, and when the company first started making lenses they named the product 'Nikkor'. So Nikkor is just 'a lens from Nikon'.
Nikonos is also a product from Nikon. It is a range of dedicated underwater cameras, that dont need a housing. The most popular one is the Nikonos V, for a long time one of the leading underwater cameras. They also made a camera called the Nikonos RS which was a dedicated underwater SLR camera. They are both no longer made, but there is still a large trade in them because they are both just damn good cameras.
If you want to know more about the Nikon lens Nomenclature check google are just type "Nikon Lens Nomenclature".
Hope this helps,
Cor
