In part three of a series on building a MEAN stack Ionic 2 Todo app hosted on Heroku, the focus is on enhancing the app's functionality with add, update, and delete features using Angular 2 components. The app's backend, established in previous parts, utilizes a Node.js server with Express to define API endpoints for a MongoDB database. The tutorial explains how to implement these CRUD operations by updating the `TodoService` with HTTP methods to interact with the API and adjust the HomePage component to reflect these changes in the interface. Additionally, the process of incorporating a new TodoEdit page is detailed, allowing users to view and edit individual todos. The overall aim is to demonstrate the integration of Ionic 2 and Angular 2 with a Node.js backend, culminating in a deployable application on Heroku. The guide concludes by encouraging users to commit their changes and deploy the app, highlighting the ease of use provided by Heroku.