Please tell me what the numbers of specifications mean , I mean : PixelPitch -Brightness - contrast ratio -viewing angle -response time , and what is the most imprtant of them ?

Answer:
For gaming you want a fast response time and a decent resolution.

For photo/video editing you want a good resolution and contrast ratio.

For general computing just take a look at the ones available and see which one you like ideal.

Answer:
In order of importance:

Contrast = how black is the black compared to the full white - if you want a good image the minimum is 1000:1

Brightness = how much light comes from the screen - in a brightly lighted room is critical, minimum 400

Resolution = the more massive the better the image quality - it's standardised for screen sizes - don't get a 19, for the same money purchase a 20, for a little more a 22. If you can get the money purchase a 24, it has a resolution superior to HiDef movies. (pixel pitch= distance between point of light, determined by the resolution; futile info for a LCD).

viewing angle and response time - old problems,now no longer pose any problem in modern LCD panels. If you want to test that just put a movie on it and move around; if something is wrong take the monitor back, you got a bad one.