While React is a front end framework that runs in the browser, some related utilities are designed to run on your own computer, using the Node.js engine. The project that creates a brand new React project, for example, runs on Node.
If you don't have a recent version of Node installed, head over to the Node.js download page to obtain it. My recommendation is that you use the latest available LTS (long term support) version.
You can confirm that Node.js is properly installed on your system by opening a terminal and running the following command to check what version you have installed: