I think there are different names for a black and white photo that shows elements of color. I always referred to them as color splash photos.
The original color photo is opened in Photoshop. Two layers of the same photo is made; one in color, one in black and white. With the B&W layer on top, selected areas of that layer are erased to reveal the color underneath.
That is a very simplified explanation of what was accomplished here with a zebra aloe plant.