Black and white photography is very often simply about shadows and light and how they create or accentuate shapes. In this sense, it can be said, of course, that colour photography is, essentially, about colours…. This takes nothing away from social documentary work, which is in a special class.
Sometimes shapes, in the case of this photograph, below (made with iPhone) lines and angles, reveal themselves. Other times you have to actually make them appear in a frame that is isolated (very briefly, and rarely objectively) from the sights and sounds of the world, and present them somewhat intact.