If an object has a mass of 20 kg, what is the force of gravity acting on it on earth?

That force is what most people would call the object's "weight".

Wherever the object is, its weight is

                            (mass) x (acceleration due to local gravity) .

On Earth, the acceleration due to gravity is   9.8 m/s² . (rounded)

The object's weight is      (20 kg) x (9.8 m/s²)  =  196 newtons .

                                                                   (about 44.1 pounds)

Go to the bathroom and vape