For the second time, Paton writes: "through hills lovely beyond any singing of it". What does he mean?

The line goes, "There is a lovely road that runs from Ixopo into the hills. These hills are grass-covered and rolling, and they are lovely beyond any singing of it." He is really just describing the wonder of the hills above one of the " fairest valleys of Africa." Paton writes about how the beauty is beyond description, beyond even a song or poetry can describe.