To find area, do length × width. In this case, 6 ft is the length and 12 ft is the width. 6×12= 72.
To write the answer in this problem, do 72 square ft, 72 sq ft, or you can draw a small 2 above the unit of measurement. -- 72 ft and then the small 2.
(for this problem ft.)
Good luck, hope this helped. :)