These xrays to the right show normal findings. On the side view (also called a “lateral” view), the spaces between the vertebral bodies appear dark because the disc material doesn’t have calcium, and the xray beams go through them. If the discs were degenerated, the spaces would be thinner, and the bones would appear closer together.
Additionally, the spine has a curve on this view that is hollow to the back, bowed out towards the front.
On the other film to the far right, which is a front view (called “AP” view which stands for Anterior Posterior, the direction of the xray beam), note that the facet joints can be seen. Also, there is no curvature of the spine to one side or the other, which if present, is called scoliosis.