The tutorial demonstrates how to use the Nexmo Voice API to create a simple voice proxy that hides a caller's real number. A business reason for this is to protect customer privacy. The process involves creating a virtual phone number, installing dependencies, defining webhook endpoints, logging call events, handling inbound calls, making webhooks accessible, purchasing a number, creating a Nexmo Voice API application, linking the application to the number, and implementing proxy logic using NCCO connect action.