Matter is made up of atoms. The interesting thing about an atom is that most of its mass is concentrated at the center, in the nucleus. A nucleus is orbited by electrons. These electrons have very large orbits. Electrons need large orbits because they exhibit wave nature and a wave is comprised of crests and troughs. Also, each electron’s position is spread over an orbital and has a range of probabilities.
So essentially, there is a lot of empty space between a nucleus and its electrons. If we were to, hypothetically, condense all atoms, by removing the empty spaces in them, the entire human population would be downsized to the size of a sugar cube. The sugar cube would be very heavy and it might not even have the same physical properties that a regular sugar cube has. But this is an interesting analogy to understand the vastness of the empty space in each atom.