Hey there! :)
The formula for area is: length × width
For squares, the length and width are ALWAYS the same.
If 1 side is 6.25, the the area is equal to: 6.25 · 6.25
Multiply:
6.25 × 6.25 = 39.0625
The area is 39.0625 ft ( 39.1 if rounded to the nearest tenth)
Hope this helps :)