Certain forms have been preserved in Hiberno-English that have disappeared from British English. "Ye" is the plural form of "you". It was once far more common in Hiberno-English than it is today, but can still be heard. Personally, I think it's a useful word that helps to avoid ambiguity.
It an outdated English pronoun that is/was an informal "you". It is still used in some dialects of British, Irish and Scottish English.