Light reflectance value or LRV is a way to measure how light or dark a color appears to our eyes. If we shine a light on an object, some of that light gets absorbed by the object, and some of it gets reflected back to our eyes. The amount of light that gets reflected back is what is measured by the LRV.
Imagine you have a white piece of paper and a black piece of paper. If you shine a light on both papers, the white one will reflect more light back to your eyes, making it appear brighter or lighter, while the black one will reflect less light, making it appear darker. The LRV is a number between 0 and 100 that tells us how much light a color reflects back. A higher LRV means that the color reflects more light, making it appear brighter, while a lower LRV means that the color reflects less light, making it appear darker.
For example, a color with an LRV of 90 is a very light color, while a color with an LRV of 10 is a very dark color. Colors with an LRV between 40-60 are considered medium or neutral colors. Knowing the LRV of a color can help us choose colors that work well together in a room, or help us choose the right type of paint for a space that needs to appear brighter or darker.