When we put a few hundred particles in a container and keep the volume the same while changing the temperature, we can see how pressure changes.
As we heat the container, the particles move faster and bump into the walls more often. This makes the pressure inside the container increase.
This idea is consistent with the ideal gas law, which says that when the volume is constant and the temperature goes up, the pressure also goes up. So, the hotter it gets, the higher the pressure becomes!