How do you determine how user-friendly a website is for most users?

If the site is difficult to use, the visitor will close it. He will not try to figure out the interface. Remember, if a user cannot find a product, he will not be able to buy it. Usability is a criterion that should be considered at all stages of website development. Do not delay usability testing https://www.plerdy.com/usability-testing-website-checklist/ until the very last moment, the later you start doing it, the more resources will be needed to fix it.