Let’s start by talking about HSV, or Hue, Saturation, Value. This can sometimes be referred to as Hue, Saturation, Brightness, Hue, saturation Luminosity, or Hue, Saturation Intensity, but all of those basically describe the same thing. It’s a way of describing color values using 3 numbers that is different from RGB. RGB describes a color using values of red, green and blue. HSL instead uses a value for Hue - what shade of color something is, saturation - or how much of that hue is present, and Luminosity/Value/Brightness/Intensity, which describes how light or dark that color is.
The luminosity value is what makes this color light or dark. A good way to think about it is that every color is really made up of a greyscale value, a color multiplier, and something that determines how much of that color affects the greyscale.