What it means
Safari website access controls where an extension may operate. Depending on the extension and Safari version, you can allow, deny or ask on specific websites. Some extensions need page access to do their job; that still makes the permission important because the extension can interact with the page.
A real-world example
A shopping helper requests access to every site, including webmail. It may work when limited to shops. Set the narrower website rule, browse normally and see whether the helper still works. If it needs unlimited access without a convincing reason, consider removing it.
What to do
In Safari → Settings → Extensions, choose the extension and open its website settings. Check private-browsing access separately. Turn it off briefly if you cannot identify its purpose, then uninstall if it is unnecessary.
The distinction that matters
An App Store listing and an extension's privacy text are not the same as an enforced per-site grant. Apple's Safari instructions explain how to manage website access and disable or uninstall extensions; the browser's permission should match the task.
Apple's Safari extension controls
