It’s been interpreted as an apocalyptic event by some but it merely refers to the end of an era in the Mayan calendar. A long era for sure – a cycle of 5,125 years since the beginning of the Mayan Long Count calendar in 3113 B.C.
The Maya was a Mesoamerican civilization, with the only fully developed written language in the pre-Columbian Americas. It also was famous for its art, architecture, and mathematical and astronomical systems.
You can still see evidence of this at Chichen Itza, which was only excavated in 1841, where the observatory can still be seen as well as the wonderful building, the Kukulkan pyramid, shown in the picture (which I was lucky to climb in the last year they allowed tourists to do so).
Modern day Mayans live in Mexico and Central America.