CMDR ISOKIX kindly presented pointed out a list of translations [created by CMDR Zebarmy of Canonn Research] for the imagery displayed on the Guardian's Obelisks. The glyphs displayed on the lighted areas of the stone show what items are needed in order to unlock the information they contain.
This diagram will act as your "magic decoder ring".
This stone requires a Thargoid Sensor and a Thargoid Link to unlock it.
So good luck in the void and I hope this information pays off. You'll be uncovering the hidden history of The Guardians in no time.
Canonn have a detailed description of what you need to do here along with maps and other advice on everything needed for Ram Tah missions.