You first need to find scenes with predominately white and black tones. In this shot, the photographer chose a scene comprised of brick/rocks (probably a middle-gray tone) and cement which is mostly semi-bright tones.
Next, the photographer choose a day with overcast lighting which is somewhat flat, but being flat (in contrast) the light won't create heavy and deep shadows nor will it create very bright highlights, both of which would not be conducive in creating this soft, lighting look.
Once the photo was captured, the photographer selected everything that he/she wanted to desaturate. Using the saturation tool in just about any photo-editing software, the photographer lowered the saturation of the selected areas leaving the model's saturation untouched. The photographer wanted to make the skin tones stand out, but he/she also wanted to keep the skin tones looking natural, too. More than likely the software used Lightroom or Photoshop, both of which offer non-destructive editing. NDE is a way of editing images without actually working on the original image file itself. It's done by editing a JPEG copy, which allows the photographer to later change any of the settings back to normal if the need should arise. The old way of photo editing was to use layers or adjustment layers, so if your client decided that the adjustments to specific areas needed changing, you could easily redo just that specific area without having to redo the entire photo. Photoshop CC and LIghtroom CC take that concept to the next level by using small JPEG copies. It's only when you are done that you can apply the edits to the actual full-resolution image and save it as a new copy. This leaves you with the original file completely unedited.