visx is an open-source visualization library for React that provides expressive, low-level primitives built on top of D3.js. It allows developers to create unique and interesting visualizations by combining basic elements such as pie, text, group, and more. visx was built by Airbnb to combine the power of D3 with React, unifying their visualization stack. It's a popular tool that outshines competitors like Recharts, offering advantages such as modularity, non-opinionated use, TypeScript support, good documentation, mock data, and simple styling. However, it may take time to grasp its architecture and learn how to combine pieces for unique visualizations. visx can be used with Cube Cloud, a headless BI tool that provides a REST API and connects to databases, allowing developers to create dashboards like the one in this tutorial. The tutorial demonstrates how to set up Cube Cloud, create a new React application, install necessary packages, and build a pie chart visualization using visx to display total orders from 2019-01-01 to 2020-01-01.