White balance is used to removing or to neutralize colors. It balances out the colors giving more warmth or cool colors. If the picture has to strong of a color cast adding white balance can help. During white balance you’re adjusting the colors along only two spectrums. It all depends on the lighting being somewhere where the light is yellow then your picture may come out a little yellow. White Balance is important because if you want a pretty picture with pretty colors you need to neutralize and keep the warmth or the coolness. You can adjust either in camera or after with editing. First you open up your image in Develop module then find the WB section. Then you select the eyedropper you then click on parts of your image that should be natural grey you can mess with it and find what you think is perfect. You can always use the temp and tint tools.