Prana, or life force,
cleanses the body mind and spirit, the chakras and channels (Ida and Pingala) of blockages to the free and natural flow of energy through them.
Prana is energy. The breath is the process by which you explore this energy. You explore its depth, its divinity, its power to purify. You explore how to reach its depths. There are hidden energies within us. These energies need to reveal themselves. They also serve purusha in different ways. That is why in the Yoga Sutras, in the Vibhuti Pada, Patanjali talks about the control you gain over these energies, such as udana vayu. If you have control over it, you float above the earth, the dust of the earth will not touch your feet. A thorn will not penetrate your foot. If there is a thorn on the ground, your foot will float. This is called control over udana vayu. And samana vayu ignites the inner fire. These are the hidden energies that connect with the five elements. The nectar will only come out of the five elements when prana connects them. Each element has its own strength, its own energy. When prana unites them, their energy rises upwards.
Pranayama is a healing process. Even if one knows nothing about it, just śavasana (relaxing in a lying down position) and observing the breath in it will activate the healing process. And then, exploring other techniques will reveal its depth. Although pranayama focuses only on the breath, there are many variations.
You cannot join pranayama in a hurry, sit down anywhere and expect something to happen. It will not happen. Because prana has its own internal laws. It gradually emerges to the surface. The practice of pranayama gradually reveals its intelligence. It is a learning process.