Raw Black Points
It is unlikely you will ever need to use the Raw Black Points tool other than for diagnostic purposes.
These sliders allow you to add offsets to the raw channel values in case the values used in the program are incorrect. You would know that they are incorrect if the colors of your image were severely wrong, for example you would see dark green instead of black, or the whole image would have a very strong magenta color cast. Cameras with a Bayer filter have two green channels, that is why there are two green sliders which are linked by default. Sometimes the two green channels are of different sensitivity, so you can unlink the two green sliders and adjust them individually.