Shadow removal removes darker areas in your pictures.
Doing shadow removal will make shadows not as strong , but can do some other neat items. It you take a picture in a darker room and do shadow removal you will find much of what was hidden in darkness revealed. When I was at the Forbidden City in Beijing several years ago and you can stand at entrances and look in dark rooms and no flash. I could see vaguely a throne and ropes. When i got back and did shadow removal my camera had seen things I had not. There as a number of pieces of furniture and an ornately painted ceiling.
You can also use it on outside photos and quite oven your pictures will get more depth and trees and such will show more as separate leaves and look more 3 dimensional and real. I shot a building one time with a row of large shrubs and no idea what was behind. When i did shadow removal I discovered people sitting at picnic tables.
Sometimes things are done with the idea that our eyes lose stuff as gets darker. I have been in theatres with no curtain behind the stage that you never noticed as it as dark area watching show, but when I had done some no flash pictures and done shadow removal the props all stored there appeared.
Shadow removal is neat but sometimes pictures are better with shadows so use discretion.