। ॥ ५१ ॥
In plain words
A strong fortress with the seven seas as its moat, rich with abundant wealth, vast and mighty, called ‘the surface of the earth’ — O Mother, I offer it to you whole.
Close to the Sanskrit
The firm fortress which has the seven seas made into its encircling moat, which is endowed with abundant wealth, vast, mighty, named 'the surface of the earth' — that entire fortress I offer to you, O Mother, by me.