What do we learn from "Omed Al Shnei Asar Bakar"?
Radak: This teaches that the bottom of the Yam was square. There were three cattle in every direction, and one side of the Yam rested on them.
Why does it say "veha'Yam Aleihem mil'Ma'alah"?
Gra: The 12 cattle correspond to the 12 Mazalos 1 ; the three in each of the four directions correspond to one of the four 'elements' (earth, fire, wind and water). [The Yam] hints to the moon, to which Yisrael are compared. In the world to come they are above; in this world they are below, just like the moon is below the Mazalos.
The Vilna Gaon elaborates to explain the correspondence of the Mazalos to the seven Kockvei Leket (the sun, moon and five closest planets) and Tekufos.
What is the meaning of "v'Chol Achoreihem Baysah"?
Rashi: Under the Yam, the backs of the cattle in the north faced those in the south, and those in the east faced those in the west.
