Create React App provides a welcoming atmosphere for learning React and is the best place to begin developing a new single-page application in the language. The first line's npx isn't a typo; it's a package runner included with npm 5.2+.
A Node version of at least 10 is required to create a React App. npm is a package management. It comes pre-installed with your Node installation. At the very least, you'll need npm version 5.2.
If you previously installed create-react-app globally using npm install -g create-react-app, you need first uninstall the package.
If you've never used create-react-app before, just type npx create-react-app myfirstreactapp into your terminal.