The mass of the moon is smaller than the mass of the earth.

That's why the gravity is lower on the moon.

Most of the moons in the Solar System are very small, but there are some large, planet-like moons. Our moon is also part of that.

The mass of the Moon is 1/81 that of the Earth.

The gravity of Mars is 3,711 m/s² and it has 2 moons.

The gravity of Jupiter is 24,79 m/s² and it has 79 moons.

The gravity of Neptune is 11,15 m/s² and has 14 moons.

More Info: en.wikipedia.org