In the video, a person is seen cutting an onion into thin slices. The person's nails are painted red, and they are using a knife to cut the onion. The onion is placed on a white cutting board, and there are already several slices of onion on the board. The person is slicing the onion in a circular motion, creating evenly cut pieces. The onion has a purple color, and the slices are thin and even.