Background image position allows you to easily control a horizontal and vertical position of your background images via Design Options. Once you add an image to your background, you will see Background style and Background position attributes available.
Combine both of those attributes to set the 'correct' position of your background images according to your preferences.
Example: If you have added a background image, but the import part of the image is not visible (due to different form and scale of image and container), you can manipulate with background image position to set correct position.
Note: Apart from Design Options, few elements, like Hero section, also have Background position attribute available.