Mass is a measure of the amount of matter in an object.
Weight is the force due to gravity on a mass.
On Earth, the force of gravity is about 10 N/kg, so a 50 kg person weighs 500 N.
Weight = mass × gravity
N.B. Mass in kilograms!
Different planets have different gravity, so the weights of objects will be different.
The mass of objects is unaffected by gravity.