Strictly speaking aerobic means in air, but it is the Oxygen in the air which is necessary for aerobic respiration.
Anaerobic respiration is in the absence of air.
Here is a molecular model of a glucose molecule. In our tissues glucose can be broken down to release energy. The energy is used to make a substance called Adenosine Tri-Phosphate or ATP as it is usually called. ATP can provide energy for other processes such as muscle contractions. Here is a balanced chemical equation for the process of aerobic respiration.