You can create banners for your website and place a banner within a Banner Module.
Your Banner Module is used to display the banners that are managed by the Banners Component in your site administrator area.
When you want to try something such as a new module, set the access level to "Special", publish the module on a specific page of your website, and then log-in to the front-end of your website, navigate to the page where you published the module (in this case) and you will see the Module but no-one else will see it.
If and when you are happy, set the access level to, for example, Public where everyone will see it.
In Joomla version 3.10.x Modules are created and managed via the administrator area menu 'Extensions' tab.