It's a translation of the phrase "Sky Above, Voice Within." It's a shortened version of, "Lok bo, Thu'um Tum." This can be seen on the banners in High Hrothgar.

Yup, it's pretty much a motto for the Greybeards. Think of it as Skyrim's version of "May the Force be with you."

I don't know much about Skyrim (then what am I doing here?) so what I meant to say was, Does the phrase mean anything, or is it just a motto for High Hrothgar?