TYPO3 9.5 supports search engine friendly URLs right out of the box. RealURL - the extension that was most widely used to generate URLs for TYPO3 8.7 and below is no longer compatible to the newest TYPO3 version.
When saving a page in TYPO3 9.5 the system uses the page title to generate a so called slug - a URL handle for that page - from the page title and keeps it indefinetily.
If you save the page without entering a page title a placeholder (like default-f0f537e0ea) is being used. So if your URL looks like this, you have probably saved the page before entering a page title. This most commonly happens when the page type is being changed before a page title is entered (and therefory TYPO3 saves the page and displays the different page fields in the backend).
Changing a page's URL in TYPO3 is pretty straightforward: Just edit the page and change the slug. You can also just click the reload button next to the slug to let typo3 automatically generate a slug based on the page's parents and the current page title.