The Home screen is where you can start, join, and schedule meetings. The other tabs at the top of the screen will bring you to other screens in the app.
This tab displays your personal meeting ID and lets you start a new meeting using it. It also lets you schedule a meeting for later and lets you access meeting recordings.
When you're finished using the Zoom app, you can just close it. If you're sharing your computer with someone else that needs to use Zoom, make sure to sign out.