This tutorial series is about building an analytical web application with Cube.js, a data analysis and visualization platform. The second part of the tutorial covers adding Funnel Analysis to the application, which helps analyze behavior across the customer journey by tracking user progress through a series of events or "funnels". To build funnels, the authors use Cube.js's Funnels package, which allows for dynamic generation of SQL code and pre-aggregations to improve query performance. The authors also discuss visualizing funnel data using Recharts library and generating a cube with conversions and steps measures. The next part of the tutorial will cover building a dashboard and dynamic query builder, while the final part will focus on deploying the application in serverless mode to AWS Lambda.