Hi Anvers,
When working with a website a “binding” is the combination of protocol (http, ftp, https, etc.), IP address, TCP/IP port and host name– which is basically a domain name. The binding is then associated with a website which allows IIS to properly route incoming traffic to the correct site.
Here is a link for what you are referring to: https://learn.microsoft.com/en-us/powerapps/maker/portals/configure/website-bindings
Hope this helps