During a neurological exam for facial pain, twitching, numbness etc she noticed my eyebrows & mouth are asymmetric. What does that mean?

Your human. Most people do not believe this but your face and body is asymmetrical and this is normal. Do not be alarmed as this is just your normal anatomy.
Normal. Asymmetrical means that the right and left sides of your head/face are not perfect mirror images. Don't worry about it though. This is normal for just about every human being on the planet.