What is the small mass of food that enters into the esophagus is?

The small mass of food that enters the esophagus is called a "bolus." This bolus is formed in the mouth as food is chewed and mixed with saliva, making it easier to swallow. Once swallowed, the bolus travels down the esophagus through a series of coordinated muscle contractions known as peristalsis, eventually reaching the stomach for further digestion.