What are Y signals?

In component video signals, there are three cables through which the signals are transmitted that are RGB, that when converted becomes YPbPr, where Pb represents blue and Pr, represents red and Y is the color of green which transmits the brightness information of the signal. It is the basic black and white part of the video unlike others it doesn’t transmit the color green. Defined by CIE in relation to human vision. It is used to measure the brightness, this is specifically used to represent the video.