Color, contrast, and sharpness retouching.
We have our own photo lab in our brain, which intensifies and separates colors when we’re there. So we will see the nuances of many colors, which the camera will not display. Thus when we see the print of that gorgeous sunset, we don’t experience the same wonder that we did when we were there. We are able to recreate that in the image so that it will convey more of what you saw when you were there. It may be retouched, but it presents a more truthful representation than the dull and lifeless ‘standard’ image.