Digital screens have the benefit of being backlit, which provides a greater light and colour range. For example: when you shoot a backlit portrait (with the light source behind your subject), the image will look OK on your smartphone. But, when you print an image like this, it's safer to lift the shadows a bit to bring back details on darker areas. This will improve the quality and balance of your image for printing.
Most photo editors have a dedicated tool for this purpose, but you can always use the "Shadows" tool from our in-app editor to bring up the brightness. Take a look at the video below for more details.