The tutorial explains how to build a basic geolocation backend using Node.js and Express by leveraging the IPWHOIS.io API from the RapidAPI Marketplace. It details the process of setting up a Node/Express environment, installing necessary packages like Unirest for handling API requests, and creating an endpoint to fetch geolocation data based on the user's IP address. The tutorial emphasizes the simplicity of integrating the IPWHOIS.io API into a Node application, allowing developers to retrieve user location details such as timezone, latitude, longitude, and currency. By following the instructions, developers can test the functionality locally and enhance their applications by integrating this geolocation data into a user interface or using it in conjunction with other services like Google Maps.