The document discusses how to write a first class in C++ using object-oriented programming. It explains that a class defines functions and variables and is like a blueprint for creating objects. An object is an instance of a class that stores values and allows access to class functions. The document provides an example class for calculating the sum of two numbers by getting input, processing the calculation, and outputting the result. It demonstrates creating an object of the class in the main function and calling the class functions through the object.