The Huawei P10 comes wit ha full manual shooting mode called 'PRO' mode. This mode essentially gives you more control over the camera settings. Instead of relying on the camera to make all the adjustments for you in full Auto mode, you just drag a little handle on the right, pull out the advanced camera settings and adjust them to your liking.
The Pro shooting mode allows you to control the ISO sensitivity, shutter speed, exposure value (EV), white balance, AF mode (between manual or continuous autofocus, AF-C). Having control over those settings allow photographers to capture the scene in a different way that it would had been captured had you chosen to shoot with the auto mode. In auto mode, the camera optimizes the shot for the best exposure. However, sometimes being able to shoot in manual mode make it easier and even faster to shoot certain scene.
For example, sometimes there is a complex scene where the subject is shot against a strong back light. If you focus on the are slightly on the side of the subject, the camera would pick up the strong light and reduce the shutter, which will make the subject and the image appear very dark. In manual mode, you just play with the shutter speed or the exposure value and set it up in a way that fits a certain image best. Another example is when shooting a moving subject. Sometimes you want the subject or subjects in the image to appear blurry. In auto mode, the camera is optimized for making sure that subjects are sharp and it does that by using the fastest shutter speed possible while still maintaining good exposure.
In order to be able to achieve that motion blur effect, you need to use a slower shutter speed. This can easily be done using the Huawei P10 'Pro' mode, because you can easily change the shutter speed to any value you like within the supported range.
One reason that many people prefer to shoot in Auto mode is because it's faster. Why mass around with the camera settings when there are intelligent algorithms that work behind the scene to make your photo look at its best? Well, best just means that the image will be well-exposed and sharp, but sometimes you want to achieve certain effects and make the image look different, and the only way to do it is by experimenting with various camera settings.
Overall, full manual mode just gives you more creative freedom to capture shots in the way you want them to look like, not as the camera thinks it's the best for a particular scene. Not all cameras has this feature, and even if a camera has it, you are not assured to get access to a lot of its camera settings, so it's nice to see Huawei being generous and giving users more control over a wide variety of camera settings.