On the new album Eist ("Listen") by Torc Music, there's a nice version of Ar Bhruach na CCarraige Báine by Breandán O Bheaglaigh and, I think, Mary Black, which has a parallel-texts translation in the accompanying leaflet.

I don't know which verse is in Irish in the version you've heard, but suspect it's probably the first, which translates as (my own translation):

O, westwards [or far back in the hinterlands] by a river, without lie, without doubt The sweetheart-girl is serene and gentle Whose mountain-recess is brighter than swan on wave From forehead to sole of her shoes It is she who is the stately woman who has torn apart my heart And she has left my mind sorrowful And medicine to be had will never be mine forever Since my bright love refused me.