So, as I promised, here's a small explanation of some camera technical stuff (let it be digital or analog) with Wikipedia links.
Aperture of the lens – adjustment of the iris, measured as f-number, which controls the amount of light entering the lens. Aperture also has an effect on focus and depth of field, namely, the smaller the opening [aperture], the less light but the greater the depth of field--that is, the greater the range within which objects appear to be sharply focused.
The lower the number is the more the iris is opened therefore, more light comes in
Shutter speed – adjustment of the speed (often expressed either as fractions of seconds or as an angle, with mechanical shutters) of the shutter to control the amount of time during which the imaging medium is exposed to light for each exposure. Shutter speed may be used to control the amount of light striking the image plane; 'faster' shutter speeds (that is, those of shorter duration) decrease both the amount of light and the amount of image blurring from subject motion or camera motion.
White balance – on digital cameras, electronic compensation for the color temperature associated with a given set of lighting conditions, ensuring that white light is registered as such on the imaging chip and therefore that the colors in the frame will appear natural. On mechanical, film-based cameras, this function is served by the operator's choice of film stock. In addition to using white balance to register natural coloration of the image, photographers may employ white balance to aesthetic end, for example white balancing to a blue object in order to obtain a warm color temperature.
Metering – measurement of exposure at a midtone so that highlights and shadows are exposed according to the photographer's wishes. Many modern cameras feature this ability, though it is traditionally accomplished with the use of a separate light metering device.
Usually every the camera is provided with at least 3 different metering modes. Multi metering (average light on several points on the field), Center-weighted average metering (average light on a small portion of the center field) and Spot metering (average light on a specific spot that usually the photographer picks - some compact cameras may have the spot metering fixed to the very center of the field).
ISO speed – traditionally used to set the film speed of the selected film on film cameras, ISO speeds are employed on modern digital cameras as an indication of the system's gain from light to numerical output and to control the automatic exposure system. A correct combination of ISO speed, aperture, and shutter speed leads to an image that is neither too dark nor too light.
In other words, higher the value is less light you need for the photo, but the amount of "grain" increases.
Focal Length - Digital cameras have a different focal length values than the film ones (that's due to the camera sensor being pretty much smaller than the classic 35mm film). The compact digital cameras usually uses the term "zoom" instead of focal length. Tho, when talking about SLR (Single-lens reflex) camera the usage of "zoom" vanishes and gets changed with focal length. Due to different values the SLR lenses falls in several different categories (from wide-angle to telephoto).
Well, in simple words a 50mm (non-macro) lens is around the same as an "human eye sees"
Exposure - Is the total amount of light allowed to fall on the photographic medium (photographic film or image sensor) during the process of taking a photograph. Exposure is measured in lux seconds, and can be computed from exposure value (EV) and scene luminance.
In simple words ... exposure is composed out of aperture, shutter speed and ISO value and tells you how light/dark the photo is.
When going under 0 with the EV value the photo will get more and more darker, and when increasing the EV value the photo gets more and more lighter.
For more info check the Photography on wik ^_^
Anything else that I should mention in here?