When you add new pages to your website, their random URLs are generated automatically. You can edit the URLs of your pages at the page settings.
Open Pages and navigation, select a page, and open Page settings:
Here you can insert something more specific to your page, for example:
Don't forget to save your changes 😉
If you have an e-store, your product URLs are also generated automatically - they depend on your product name and include a product ID by default. The product ID is not editable, but you may edit the product name, and the URL will change automatically.