Effusion refers to the process by which gas molecules escape through a small hole into a vacuum or lower pressure area. The discussion highlights that gas molecules are in constant random motion, colliding with the walls of their container. When a hole is created, the number of molecules that can escape is influenced by several factors. The rate of effusion is directly proportional to the area of the hole and the pressure of the gas, while it is inversely proportional to the square root of the molecular mass of the gas. Additionally, the temperature of the gas also plays a role, as it affects the kinetic energy and speed of the molecules. Understanding these relationships is crucial for grasping the principles of effusion in gas behavior.