A Maya stela is a huge stone slab with Maya glyphs and drawings on it. Each told a story. They were placed where the people could see them. It took time and effort to carve a story in rock, so only really important stories were told on a stela. Some historians refer to these ancient stone structures as stone trees.
Stelas have told archaeologists a great deal about the ancient Maya. Archaeologists cannot read all of the Maya glyphs, but they can read quite a few, and can piece together most of the story on each stela they have found.