Node.js can be installed in different ways. This post highlights the most common and convenient ones. Official packages for all the major platforms are available at https://nodejs.org/download/.
One very convenient way to install Node.js is through a package manager. In this case, every operating system has its own. Other package managers for MacOS, Linux, and Windows are listed in https://nodejs.org/download/package-manager/
nvm is a popular way to run Node.js. It allows you to easily switch the Node.js version, and install new versions to try and easily rollback if something breaks. It is also very useful to test your code with old Node.js versions.
See https://github.com/nvm-sh/nvm for more information about this option.
In any case, when Node.js is installed you'll have access to the
node executable program in the command line.