When you select the Crop from option it creates a cropping mask that will crop out everything from the selected side using the face marker such as a Nose as the starting point. For example, if you select Top as the crop side:

You will end up with an output image that just contains the top portion above the nose. Everything below the nose will be removed:

If you set the Crop side to Bottom you will end up with the an output image that contains the bottom portion above the nose. Everything above the nose will be removed:

Quick Tip: To create unrecognizable model faces for eCommerce, you will want to set the Crop side to Bottom.

Only with Crop from option can you choose top, bottom, left or right region to crop. All of this can be easily visualized using the Preview mode in the UI.