Translation:

7. He made it rage against them seven nights and eight days in succession: So that thou couldst see the (whole) people lying prostrate in its (path) as if they had been roots of hollow palm- trees tumbled down!

Notes (Tafseer)

5640. A graphic simile. Dead men all lying about like hollow trunks of palm-trees, with their roots exposed! The 'Ad were reputed to be of a tall stature.