The answer is 117.7 J.
Gravitational potential energy is the stored energy of the object as the result of its height:
E = m · g · h
where
E - the potential energy of the object: E = ?
m - the mass of the object: m = 6 kg
g - gravitational acceleration: g = 9.81 m/s²
h - the height of the object: h = 2 m
On the ground (h = 0), the gravitation potential energy does not exist: E = 0.
So, let's calculate it on the height of 2 m:
E = 6 kg * 9.81 m/s² * 2 m = 117.72 J ≈ 117.7 J