The area of a shape can be defined as the space occupied by the surface or a measure of its surface.
The square is used as the basic unit of area.
The area of an object is the number of unit squares that cover the surface of a closed object. The area is measured in square units such as square feet, square centimetres, square inches, etc.
A square of side 1m covers an area of 1 square metre or 1 m2
A square of side 1cm covers an area of 1 square centimetre or 1 cm2
For example, A rectangle 5cm long and 3cm broad can be divided into squares of 1cm as shown below.

By counting the squares, the area of the rectangle is 15 cm2
Good