Fáinne an lae, meaning dawn, literally means the ring of day, and refers to the brightness at the edge of the eastern horizon at dawn; 'geal', or gheal after the feminine noun fáinne, means bright.
The original song is an aisling poem, a style composed commonly in the 17th and 18th centuries to disguise the fact that they were songs of freedom from the occupying forces, who were fond of hanging people for wanting freedom.