Prana is air or sky/heavenly energy, mixed in your body with earth energy through your feet and plant energy through digestion (gut flora).
It is transformed by breathing deeply through yawns into your lowest chakras. Yawning clears the higher chakras to draw in energy from the crown and forehead as well.
What you breathe out can heal the energy of other living creatures. The mixing is at the heart chakra so the energy comes out in the fingertips as well as the breath.
In this way we are all, all living creatures, transformers of energy.