Mass is the amount of matter in an object. This amount doesn't change no matter where the mass is located. It can be on Earth or on the moon, but whatever the object's mass is, that would remain the same. However, weight is due to the affect of the force of gravity on an object. Weight can change depending on where the object is. Kilograms are a metric measure of weight. Someone can have a weight of 123 pounds. That would be their weight on planet Earth. However, on a smaller celestial body, such as the Moon, where the pull of gravity is one sixth that of Earth, their weight would be one sixth their weight on Earth. On a larger planet, like Jupiter, there weight would be much greater. Actually, even on Earth, at the equator their weight would be slightly different than at the poles. The closer they are to the gravitational pull, the more their weight would be. And since the Earth is not a perfect round object, but an oblate spheroid, the weight varies slightly where you are located on Earth.
Mass is the measure of what a body contains. It is constant and does not change, irrespective of whether it is measured when a body is still or in motion or where the body is kept. The SI unit of mass is the kilogram.
Weight on the other hand is the force that is acting on a body. For example the force due to gravity accelerates a body with a mass of 1 kilogram by 9.8 m/s^2. This is defined as a force of one Newton.
Kilogram is the measure of mass. A body with a one kilogram mass weighs 9.8. Pound on the other hand is a unit of force or is your weight
Mass is the amount of matter contained in an object. This quantity of matter does not change with the change in position of the object on the earth.The mass of an object can be measured by direct comparison with a standard mass using a lever balance.
In contrast weight is the amount of pull exerted on the object due to gravitational pull. This pull varies with the variation in gravitational pull at different places on earth. weight of an object can be measured using a spring balance, as the same object will create different amount of tension in the spring of the balance as the object is moved place to place.
Thus though weight and mass are two different things, often the same name like kilogram or pound is used for unit of measurement of these quantities.
Thus kilogram can represent mass as well as weight. Also note that for all practical purposes the value of mass and weight of any object are same.