Replit, a browser-based IDE, supports multiple languages and execution environments, including a simple key value store for data persistence. To access larger amounts of data or use powerful query tools, users can interact with relational databases like Supabase without worrying about servers or hosting. By following the steps provided in this text, Replit users can set up a Supabase + Node.js repl and start communicating directly with their database using JavaScript. The text also offers challenges to help users learn more about the query interface and provides examples of how to use different filtering options.