Drush is the command line shell and Unix scripting interface for Drupal. The most common way to install Drush is to install it on a per-project basis using Composer. We'll walk through the steps to do that, as well as how to set up the Drush Launcher tool (to make it possible to execute Drush commands without having to specify a full path to the executable).
Run composer require
composer require drush/drush
Once that's completed run the command ./vendor/bin/drush --version to verify it worked.
/vendor/bin/drush --version