The way it works is simple: select the region you want to edit, choose the colors you want to remove, and wait for the application to process the change. Thanks to the application's restoration algorithm, the rest of the image will remain untouched.
A great example of a situation in which this application is incredibly useful is with photos taken with digital cameras that put the date in yellow in the corner. To get rid of the date, simply select the area where it appears, choose the color of the text, and process it. Unless the background is super complicated, the application can usually remove the text without a problem.