One kilobyte equals approximately 1,000 bytes of stored data (photos, video, words, art, etc.) 'Kilo' comes from the Greek word, chilioi, meaning one thousand.
The cylinder-shaped part on the front of the camera through which light enters, so you can see the picture you want to take on the viewfinder and which strikes the camera sensor to record the picture digitally.
This is another scale on a lens. It consists of a series of lines, one for each of the f-stops of your lens, and two marks of equal distance to the right and left of each f-stop.
This is an unwanted reflection of light that you may see in the viewfinder or not until you view your picture. A lens hood will help you reduce or eliminate lens flare.