This slab of carved stone was located in a tiny museum, in a tiny little colonial town called Valladolid, in the Yucatan Peninsula in Mexico.
The museum is a one room exhibit, in very poor condition, and offers other items such as old spanish guns found in the region, mayan artifacts, canon balls, some texts, etc.
I found it puzzling, because there are other Spanish-era writings, and you can clearly tell it's Spanish, even if old-style. It was only 500 years ago or so.
But this slab I can't for the life of me figure out what it says or what it is. And there was no one to ask there, so I come to you.
It may be worth posting this in /r/whatisthisthing as well.
It looks like old Spanish, but I can't read it either. I wonder if it might have a meaning at all: it could be just a test slab for a craftsman (see e.g. the two Ð on the right side, without context). It could also be that the black ink does not follow the markings with accuracy and is misleading us.
