Function of second lens on iPhone X

Anyone that knows what the function of the second lens on the iPhone X is? I know it is supposed to be a different focal length, but when I hold something in front of the second lens and zoom, it doesn't seem to be used. There are only a few times I've seen the second camera being used when I zoom or just use the camera, but to me, it looks a bit random.

Please let me know if you have any answers, thanks in advance! 🙂