I'll save a full in-depth article about white balance for another day but essentially light comes in different temperatures. A light bulb gives a different temperature of light (cast) to the sun or sun through a cloudy sky or strip lights. The human eye and brain are very good at filtering this so you see white as white but the camera is not so clever so it takes a guess based on the colours in your picture. In most situations this works fine but adjusting the white balance yourself can provide better results and some interesting effects. I took this picture and then changed just the colour temperature and tint between each image to show the effects of white balance on a photo. White balance is normally reserved for getting the whites white but it's more of a creative choice. These show so extremes that give stronger colour casts but it's worth trying tweaking the white balance to change the effect more subtly.
Below I have changed the white balance just a bit between each picture to change the feel from cooler to warmer to give the pictures a different feel without making the pictures feel unnatural. Which is right? Well both - it's a creative choice it depends what feeling you are trying to communicate a cool winter day or a sunny afternoon.