If I weighed 60kg on earth how much would I weigh on Venus?
Venus is approximately the same size as Earth but its mass is about 81% of Earth's.
The conversion factor for weight on Earth to weight on Venus is approximately .91.
Thus you would "weigh" `60*.91~~54.6"kg"`
Note that kilograms are the units for mass -- your mass would not change in going from Earth to Venus. However your weight, the force exerted, changes since Venus has less mass than Earth and thus pulls on your body with a weaker force. The amount of force can be calculated using Newton's law of gravitation -- the force is inversely proportional to the square of the distance between the two objects and directly proportional to the product of their masses where the constant of proportionality is the universal gravitational constant.
The mass of an object is measured in kilogram. The weight of an object on the Earth or on Venus is the gravitational force that pulls it towards each of the planets. Weight is expressed in terms of newtons.
If your mass is 60 kg, it will remain 60 kg on Venus also. The gravitational acceleration on the surface of the Earth is 9.8 m/s^2. Force is the product of mass and acceleration. Your weight on the Earth is 60*9.8 = 588 N. The gravitational acceleration on Venus is 8.83 m/s^2. Your weight on Venus would be 529.8 N.