For a certain amount of time, scientists did not think that this form of writing meant anything, but one Russian did.
Yuri Valentinovich Knorosov (1922-1999) believed that these symbols were part of an alphabet that was partly phonetic, meaning that each letter stands for a sound. Many of his fellows did not believe him, but he was proven right. Further progress in the decipherment was made during the 1970s and 1980s, when more linguistics began to take an interest in the script.
Today, most Mayan texts can be read, though there are still some unknown glyphs.