What does value mean?

Any landscape has to have values. This gives it depth. Values are not colors. Values are various color strengths as you proceed to the background of your painting. Adding white to a color changes its value. You can also do the same by adding its complement, but it's easier to just add white. Usually the colors get lighter the farther back they are. These are what are called value changes. Most objects have value changes. At least three are required to make the object stand out.