A page from the Madrid Codex
It's possible that the Maya learned how to write from the Olmec, but there aren't any examples of early Olmec writing, so more likely it was the Maya who invented writing in the Americas. Like most other writing systems, Maya writing is a syllabary, not an alphabet (compare Sumerian cuneiform or Egyptian hieroglyphics or Chinese.)
Maya writing is not very difficult to read once you get some practice. You can begin by reading the numbers. One dot means one, two dots mean two, and so on. A bar means five, and two bars on top of each other mean ten.
Now you can begin to read words. The main root part of each word is in the middle of the picture, and then prefixes and suffixes like un- or -ing are added on around the corners and edges.
Maya people used their writing mainly to carve inscriptions on their stone buildings telling who made the building and when.