Complex sentence: Saliva moistens the food and begins the digestive process, the food is then swallowed down the esophagus into the stomach, where stomach acid and enzymes help to break down the food.
Split into simpler sentences: Saliva moistens the food and begins the digestive process. After being swallowed, the food passes from the esophagus into the stomach, where stomach acid and enzymes help to break down the food.