Hi, Villan - all PP&M lyrics are available at http://www.peterpaulandmary.com. I posted the PP&M lyrics for this song here (click) [and I see you posted them here (click) ].

As for meaning, I think they mean the same as many similar lyrics in Irish songs - nothing. I think the words most frequently sound more like "shule aroon." I guess you could almost call them "mouth music," although actual mouth music is a little more sophisticated. Certainly, it conveys a strong tone of sadness, but I don't believe the words have any particular meaning. Note all the other threads on this song - in the crosslinks at the top of this page.

Pay special attention to the notes from Belden in the Digital Tradition entry here. Apparently, Belden thinks they have meaning, and who am I to disagree with Belden? Belden says "Shule" (siubhal) means walk or come. He won't commit himself to a further interpretation of the meaning, but he does give a possible Gaelic source and translation (see DT).
-Joe Offer-