At the lowest levels, we see scenes from everyday life and the appearance of the Buddha in the world of samsara (kamadhatu).
At the higher levels, we see various Buddhas and bodhisattvas (rupadhatu).
At the highest levels, we see the Buddhas enclosed in stupas (final enlightenment)/
The topmost stupa on Borobudur is empty, seemingly representing the ultimate emptiness (shunyata) of Mahayana doctrine. We can understand that emptiness as the final state of consciousness in the Mahayana path.
Altogether, Borobudur has 2,672 panel reliefs (separate scenes carved into stone), and 504 Buddha statues.