This lecture covers the representation of structured data in programs, such as age, name, height, and gender. It explains how arrays can represent homogeneous data structures and introduces the concept of structures to group heterogeneous data. Examples of structures like Date, Particle, and Student are discussed, along with the declaration, initialization, and access of structure fields. The lecture also demonstrates a complete example involving a Person structure, functions for birthday increment, and display. It concludes with the usefulness of structures for heterogeneous arrays and handling functions with multiple return values.