The number of square units in the polygon gives the area of the polygon. It is easy  to  distinguish between perimeter and  area. Just think a perimeter as a fence length you need to cover the yard, the space inside the yard is the area. Area has both length and width and hence it can be measured in square units and expressed as square inches, square feet or square meter.

Area of Rectangle

Formula for the Area of a Rectangle = $ L \times W $

Where L is the Length and W is the Width.
Steps for finding the area of a rectangle:

Step 1: Measure the length of the rectangle.(The longest side of a rectangle will be its length.)

Step 2: Now take down its width. That is the rectangles shortest side.

Step 3: Now multiply the length measurement with the measurement of the width. The product is the area of that rectangle.

Step 4: The area is always expressed in square units. Such as, if the length and width are measured in inches then the area will be in square inches and if they are in meters then they are expressed with square meters.