Okay, so imagine you're drawing a picture with colored pencils. You have lots of different colors to choose from, right? But now think about what happens when you add a bunch of different colors together. The result might be a brownish color that doesn't look like any of the individual colors you used.
The same thing can happen with the colors on a computer screen or in a photograph. There are lots of different colors that can be shown, but when you mix them all together, you might end up with a slightly different color than you intended. This overall color is referred to as the "white point."
When we talk about white point in technical terms, we're usually talking about the color temperature. This is a measure of how "warm" or "cool" a white color appears. If you've ever looked at a light bulb or a computer screen and thought it looked a little yellowish or bluish, that's the color temperature.
In some cases, it's important to get the white point exactly right. For example, if you're doing professional photo editing, you want to make sure that the colors you see on your screen match the colors in the original image as closely as possible. In other cases, it might not matter as much.
Overall, white point is just a way of talking about the color of white on a screen or in a photograph. It's something that people who care a lot about color spend a lot of time thinking about, but for most of us, it's just one small piece of the bigger picture.