The reference to the 'Spanish Lady' is thought to refer to the black hair and Spanish looks of the woman in question. It is generally accepted that she was a 'lady of the night’.

She had a heart so filled with loving, And her love she longed to share,
And in all my life I never did meet with a maid that had so much to spare.

I have heard it said that the reference to the counting of the numbers is, that the singer in counting the odd numbers and the even numbers separately, he was saying that the lady had 'both the odds and evens of it', in other words that she had everything.

How many songs does Frank Harte sing?