PlanetScale is an advanced MySQL-compatible database service powered by Vitess that provides scalable solutions for applications, and this tutorial guides users on how to connect it with Retool to build internal tools and dashboards. The process begins with setting up a PlanetScale database, followed by creating and configuring a MySQL resource in Retool, ensuring secure connections using SSL/TLS and a CA Certificate. Users then utilize Retool's Query Library to seed their PlanetScale database with tables and sample data, enabling the creation of a basic schema with teams and players. Once the database is populated, a Retool application is developed, where queries are created to retrieve and display data dynamically. The tutorial emphasizes the potential of combining PlanetScale and Retool for building powerful internal tools, encouraging users to explore further possibilities through community forums and additional projects, such as integrating Retool with Square APIs for a ticket-selling dashboard.