Area is the measure of how many squares fit in an enclosed flat space.
If we use square pieces that measure 1 inch on each side, so the units of the measurements are called square inches.
So in above example, the measure of each side of the yellow square is one inch. Therefore, we can write that the are is 12 square inches.
So can measure area with square inches, square centimeters, square miles, or even square units, as long as the length of the units are defined.