"Gaelic" is not a verb.
Caileag is 'girl'.
do chailín
One word for girl is 'caileag'.
caileag
In Irish 'cailín dubh'; in Scots Gaelic: caileag dhubh.
The Celtic word for girl is "cailín" in Irish Gaelic.
Caileag mhath -- (A) good girl
Bancheamaradóir
soith, bitseach
In Scottish Gaelic it means "my brown-haired daughter" or "my brown-haired girl". In this case it most probably means "my brown-haired girl", since this is the title of a Gaelic love song. By the way in modern Gaelic grammar it should be "mo nighean dhonn", because nighean (girl) is feminine.
lucky girl is "cailín ádhúil" in Irish; Scottish Gaelic: ...