TVL is the term for tv lines. Its the number of horizontal "lines" on the screen to make the picture. Lines of resolution. Older cameras were 480 tvl when newer ones supposedly go up to 1200 right now and price reflects it. The more "lines" the more compressed, the more compressed the better the picture. Computers use the term "DP" but is pretty much the same thing. They utilize "dots per". The more "dots" the better the picture. The mm is the size of the lens. The smaller the number, the smaller size the lens measures across. Not the glass or outer cover, but the inner working part. Focal length is basically how far it can see focused. Then you have the angle. The bigger the number, the "wider" it will view.
Now we have digital. 1080P, 720P etc... The "P" is basically referring to pixels. The more pixels the better the picture. Have you ever seen a computer screen with a weird colored dot somewhere on it? Or heard the term "Dead Pixel"? That's 1 single dot gone dead.