The words Bhumi (earth), Antariksha (sky), and Dyu (heaven) form eight syllables. One foot of the Gayatri consists of eight syllables. This (one foot) of it is that (i. e. the three worlds). And he who thus knows that foot of it, conquers as far as the three worlds extend.

In plain words: The words for earth, sky and heaven together make eight syllables, just like the first line of the Gayatri, a sacred verse. Whoever knows this line as the three worlds wins everything those worlds contain.