How many keywords can a website have?

You can use up to 3 4 keywords but try to make your content more informative rather than focusing only the keywords which makes no sense. Take help of Meta Title & Description. You can target your keywords in title and description.

For More Information Please Refer: https://www.quora.com/How-many-keywords-can-we-use-for-each-page-in-a-website-for-SEO