That can be a tricky question to answer! Mass is the amount of matter in a particular object. Weight is your mass multiplied by the pull of gravity. You will weigh a certain amount standing on earth, but if you were standing on Mars you would be lighter and if you were on Jupiter you’d probably be squished to a pulp as your bones wouldn’t withstand the force of gravity.
Given that Mars is suspended in space, it technically doesn’t ‘weigh’ anything! However, Mars has a mass of 6.4191 × 10^23 kilograms. Written out fully, it has a mass of 641910000000000000000000kg or equal to 0.64 Earths.