What do the following lines (1349 – 1365) mainly tell us about grendel in the epic poem beowulf?

land-dwellers here and liegemen mine, who house by those parts, i have heard relate that such a pair they have sometimes seen, march-stalkers mighty the moorland haunting, wandering spirits: one of them seemed, so far as my folk could fairly judge, of womankind; and one, accursed, in man's guise trod the misery-track of exile, though huger than human bulk. grendel in days long gone they named him, folk of the land; his father they knew not, nor any brood that was born to him of treacherous spirits. untrod is their home; by wolf-cliffs haunt they and windy headlands, fenways fearful, where flows the stream from mountains gliding to gloom of the rocks, underground flood.