The mass of an object is the amount of matter packed into it. All objects in the universe have mass. Weight is determined by an object's mass and how much gravity is pulling on that mass. Heavy objects have lots of mass.
Light objects have less mass.
Pick up the red and blue blocks. Put one in each hand. Let's find out. Put the red block on one side of the scale and the blue block on the other side of the scale. Take the blue block off the scale and replace it with the four smaller green blocks.