Linguistically, the song name is a bit dodgy. The phrase 'Erin go Bragh' is commonly used but really 'Éire go bragh' would be better (allowing for some kind of 'Anglicised' spelling

In Irish, Ireland is called Éire (among other names), 'Erin' is derived from forms such as 'in Eirinn' (in Ireland) or 'muintir na hÉireann' (the people OF Ireland).