Aperture: This is a strange one, and it is basically the one that has the f/ before the number.
Basically, if the number is low, the lens will let more light into it, allowing you to take photos in darker conditions without having to suffer shutter speed and use flash. The lower the number, the smaller the depth of field. The higher the number, the less light, but the bigger the depth of field. This is a good photo to describe it, the top having a big F/ number and the bottom having a small F/ number.
ISO: This is the sensitivity to light. Basically, the lower the number, the less sensitive to light your camera is, but the more detail it will retain. The higher the number, the more sensitive the camera is to light, but the picture will often have a lot of noise. The one on the left is taken at ISO 100, whereas the one on the right is taken at ISO 3200 (the shutter speeds and aperture has been changed to keep the light meter happy)
White Balance: This is the process of removing unrealistic colour casts from your pictures. Basically, what you see in real life is white, will be replicated as white on the camera, as long as the white balance is right. You can set white balance yourself, but I put it on automatic
f/stop: I do believe that this is to do with aperture. Correct me if I'm wrong
Exposure: Its just like film. If not enough light is on the film, the photo will appear dark. If too much light is on the film, the photo will appear too bright. Getting just the right exposure is down to knowing what settings to use at the right time (its down to constant use
) or using the inbuilt light meter. Read yer manual
Shutter Speed: This is basically how fast the shutter opens. 1/250 means the shutter will open for 1/250th of a second. 5'' means the shutter will open for 5 seconds. This basically allows less/more light into the camera. To reduce camera shake, you want to use a shutter speed equivilent to the focal length at the current time. If you're using your Sigma 10-20mm wide open, a shutter speed of 1/10 should stop camera shake being a problem, but if you're using your Nikkor 70-300mm at 300mm, you'll want a much higher shutter speed, somewhere between 1/250 or higher.
Keeping EVERYTHING in focus uses a low aperture - a high f/stop. But focusing, you either use manual focus or auto focus. Depending on what you're shooting really.
Hope that clears it up for you