The vagus nerve is actually two sets of nerves that drive the parasympathetic nervous system, or the part of the nervous system involved in slowing down and calming the body’s responses to the world.  Stimulating the vagus nerve means triggering the process of calming, and this process has been the subject of intense interest over the past few years, because it can be involved in things like lowering stress, reducing depression, and reducing seizure activity.

Discussion of the vagus nerve can be complicated, but this lifestyle article from The Cut offers an enthusiastic and simple explanation of why this is good and important.  Check it out here:   https://www.thecut.com/2019/05/i-now-suspect-the-vagus-nerve-is-the-key-to-well-being.html