We are never told exactly what this symbol is or means on the show. But it appears to depict the rock formation where the pods and Granolith were housed.
It is seen in the visions of the symbols in the desert that the podsters have.
It is also seen in Nasedo’s cave painting
And of course in Max’s drawing of the cave painting
~*~*~*~*~*~*~
I assume that this symbol represents the Granolith chamber and
since so much of season two focused on the translation of the book and going home,
not to mention the culmination of the season saw the destruction of the mountain,
I decided the mountian symbol was an appropiate representation.