What is the purpose of the universal gravitation constant in newtons law of universal gravitation?

Universal Gravitation Constant is just a constant. Similarly, like the constant we use to change different currencies. To change a dollar into Euro, you have to multiply a certain number to it. This is called a constant.

The more appropriate reason can be to get an accurate value. Without the constant, you wont get a correct value for the gravitational force acting on an object.