Note these commands are mentioned in Cypress installation guide Installation, here are just briefly mentioned commands you will need for your work with Cypress. You will need those commands for running your tests so they are really important, not just for installation.
to open the new Terminal in Visual Studio Code, just click on Terminal - New Terminal , see the following screenshot from Mac:
npm cypress open - this command opens a new window with Cypress runner, it will show you all you tests you can run. The window looks like this:
npm install - this command is used during installation and also when you want to update your Cypress to the latest version. It says to Node Package Manager to look into package.json file and download all devDependencies.