how do i find keywords on a website properly?

Depends whose website. Your own: Search Console, Performance report, Queries tab. That's the real list of searches you showed up for, straight from Google. Click into a page first if you want the queries for just that URL. Someone else's: you can't see their data, so you're relying on estimates from tools like Ahrefs or Semrush (organic keywords report for the domain or URL). Fine for direction, not exact. For a quick look, the page title and H1 usually tell you what they're targeting.