The 323(200) is the published minimums for the approach. The 323 is altitude (above sea level in feet and referenced to the hectopascal setting you have on your altimeter). In this case the ground elevation would be the difference between being 123 ft in this case. The (200) is height above ground. You would fly down the approach and on reaching that minima you need to either have established visual reference or go around. The 800 is visibility in metres. The visibility would have to be equal to or better than that published to be able to commence the approach. The 550 RVR is runway visual range and is a more accurate assessment determined by transmissiometers located alongside and parallel to the runway. RVR would be used when the visibility reduces to below 800m and is used for low visibility approaches in an aircraft approved for auto land. The A B C D is the performance category of the aircraft for determining approach minima. Basically it is the speed range based on 1.3 times the stall speed in the landing configuration and at max certified landing weight. Smaller aircraft are A to B (GA piston aircraft and turbo props etc). C would be 737 and A320 types and D would be the heavies like 787s and 747s. You could just google for your aircraft type approach performance category.
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Navigraph chart videos