These (the different colours in the sun) are the essences of the essences. For the Vedas are essences (the best things in the world); and of them (after they have assumed the form of sacrifice) these (the colours rising to the sun) are again the essences. They are the nectar of the nectar. For the Vedas are nectar (immortal), and of them these are the nectar.

In plain words: The colours in the sun are the best of the best. The Vedas are the finest and most lasting things in the world, and these colours, which rise from the Vedas through sacrifice, are their finest part, the nectar of the nectar.