Meant by INSTANCE in the entity type?

What is meant by INSTANCE in the entity type?

A single occurence of an entity type is called the entity instance. An entity type is described just once in a database, whereas many instances of that entity type may be represented by data stored in database.

For example, there is one STUDENT entity type in many universities, but there are hundreds (or even thousands) of instances of this entity type stored in the database.