The formula to find the area of a square is:
[tex]\begin{gathered} A=s^2 \\ \text{ Where A is area and} \\ s\text{ is a side of the square} \end{gathered}[/tex]So, in this case, you have
[tex]\begin{gathered} s=7ft \\ A=s^2 \\ A=(7ft)^2 \\ A=49ft^2 \end{gathered}[/tex]Therefore, the area of the floor of the closet is 49 square feet.