Bugger - thought we'd trapped all the typos and errors!
Well spotted, Kam.
It should read: One Priest Level benefit is granted - the teaching of a Cult rune.
However, as runes were extracted from the core rules, and will appear in the Magic Book, that whole sentence should've been chopped.
I think that, for now, and until the Magic Book appears, you should give Priests a free Advanced skill, pertinent to the cult, at its starting value.
The book 'Cults of the Young Kingdoms' (no, haven't started it yet - later this year) will expand on all the cults, and provide new ones, and will go into more detail on the such things.
But apologies! It should've been expunged.