The Maya were known for their bark (huun) codices that closed like an accordion. They were read from left to right and with a little help from early Spanish colonialists, the glyphs themselves were only able to be efficiently deciphered since the 1980s.
Below it what the sign read:
One of the characteristics of the Mayan culture was the development of a writing system which left traces in several ways. It was carved or painted on stelae (stone monuments), altars (circular stone slabs associated with stelae), lintels (stone over doorways), walls, stairs, thrones, objects of personal adornment (ear spools and jade plates), codices, and even on the body.
A close look at these pages make them seem almost like comic books. There is a scene depicted with glyphs around them to enhance the story.
The only Mayan I know how to read are the numerals. Spot any of the bars with dots over them. Each individual bar represents the number 5, whereas each dot represents one. It’s a lot like Roman numerals where you add the numbers up to get the one that is meant to be depicted.
For instance, on the top of the page with the dark figure, there is a row of two bars with three dots over them. Each of those represent the number 13. If that is a is part of a calendrical date or a count on goods, I have no idea. I suppose it could also be the name of the deity or elite seen in the particular scene.
(uploader´s note: description/text is only from flickr page, not from scientific source. Number 13 mentioned there, can surely refer to a 13 moon calendar…)