In ancient Hindu general science, the universe was seen as being composed of elements. These were not the same elements we have in our chemical Table of Elements. Rather they metaphorically described similar manifestations observable in the creation. They were called space, fire, water, wind and earth. Space is pretty easy to understand.
Fire is any brightness, heat, energy, or transformation.
So this could include sunlight, atomic energy, digestion, or electricity as well as flame. Water includes all liquids. Wind includes all movement, of air but not just air. Perhaps it also includes all gases. Earth includes all tangible material not just dirt.