An Paistin Fionn means "the fair-haired one", and in the second line of the chorus, "is mo gra gheal" is "are my heart's desire" or something to that effect--that's all I know. I have a copy of the words, and I think that either they're written phonetically on my sheet or this is a rare example of Gaelic sounding the way it looks, but here it is: "Is tusa mo run, mo run, mo run/ Is tusa mo run is mo gra gheal." Hope this helps.