The Box projection is an extension of XYZ To UVW mapping - the projection of the cube's planes are based on the normal direction of the surface. Box projection provides a quick way to map a texture on any object without too much distortion. However, the seams between the projection planes of the box may be visible in the render, depending on the shape of the surface. The following image is from the Standalone version of Octane (figure 1).
Figure 1: Applying a Box projection to a Checks texture