This is the formula for the area of a circle where,

A is area

3.14 is `pi`

r is the radius of the circle.

This is the formula that is used to find the area of a circle.  It means area (that's the capital A) equals pi (which has been abbreviated to 3.14) multiplied by the square of the radius (remember the radius if the distance from the center of the circle to any point on the circle - or half of the diameter).  You have to follow the order or operations (PEMDAS) - so make sure you square the radius first (multiply it by itself) and then multiply by 3.14.

This is an equation of the area of a circle with a radius of 'r'.

3.14 represents the value of 'pi'. 

Conventionally, area of a circle is given as:

`A = pir^2 = pi/4 d^2`

Where A is area, r is radius, and d is diameter of the circle. The diameter is exactly twice the radius of the circle, i.e. d = 2r.

Hope this helps.