If he meditate with two Mâtrâs (A+U) he arrives at the Manas, and is led up by the Yagus-verses to the sky, to the Soma-world. Having enjoyed greatness in the Soma-world, he returns again.

In plain words: Someone who meditates on the first two sounds, A and U, goes after death to a heavenly world called the Soma-world. After enjoying it for a while, that person comes back to be born again.