Here's why:

* C6H6O6 represents glucose, a simple sugar that serves as a primary energy source for cells.

* 6O2 represents six molecules of oxygen, which are essential for the process.

* 6CO2 represents six molecules of carbon dioxide, a waste product of respiration.

* 6H2O represents six molecules of water, another waste product.

Cellular respiration is a complex process that occurs in multiple steps within the mitochondria of cells. It breaks down glucose in the presence of oxygen to produce energy in the form of ATP (adenosine triphosphate). The overall equation you provided represents the simplified summary of this process.