What is a domain Alias?
This page explains all about domain aliases and how they are relevant to WordPress websites.
For example, if you have two domains for your flower shop business, you can "map" the second domain as an "Alias" of the primary domain. Website visitors will see the Alias in their URL bar when navigating the site.
Here's how to configure a domain Alias on your hosting cPanel:
When you have a WordPress website (or website of any kind), you can assign Aliases to your website. However, not all servers are ready "out-of-the-box" to map domains to a single website and require additional configuration.
Furthermore, your WordPress website needs some extra configuration to "map" each alias to a specific "post" in WordPress (or group of posts).
At the end of the day, the purpose of creating an Alias domain on your server is to map multiple domains to a single WordPress installation.