Here's what the map reveals:
* The location of the treasure: The map leads Bilbo and the dwarves to the Lonely Mountain, where Smaug the dragon is guarding a hoard of treasure.
* The riddles of the door: The runes also contain the riddles that need to be solved to open the door to the dragon's hoard.
* The secret passage: The map reveals a hidden passage that leads to the treasure chamber, bypassing Smaug's lair.
So, it's not the map itself that "speaks", but the runes on it that reveal the secrets of the treasure.