A homepage is the main page of your website, the address of which is (usually) your root domain:
The address of your homepage is
https://domain.tld
Meanwhile, the address of any other of your website pages would be
https://domain.tld/contact
,https://domain.tld/about
, etc.
Using Hostinger Website Builder, you can easily set any page as a homepage in the page settings.
Within the builder, expand the Pages and navigation panel on the left, find the page in question, open its settings, and select Make homepage:
Once you set a new page as a homepage, the home icon appears next to its title. The previous homepage becomes a regular page:
You can also rename the homepage (and other pages) in the page settings. To change the display order of pages, drag them up or down by the six-dots handle.