KEV helps you by letting you know what the white balance should be. You can measure the color temperature of a light source in kelvin without having to spend hundreds of dollars on professional devices.
Trying to get perfect white balance on your DSLR can be annoying. KEV helps you get true colors when taking photos and keep consistent shots with accurate white balance. The white balance is a correction of color rendition to make the picture from the camera sensor as similar to the perception by human eyes as possible.