There is no specific number of keywords that a webpage should have in SEO. Rather than focusing on a specific number, it is more important to ensure that your keywords are relevant, specific, and used naturally throughout your content.

It's also important to avoid keyword stuffing, which is the practice of including too many keywords on a webpage in an attempt to manipulate search engine rankings. This is considered a black hat SEO tactic and can result in penalties from search engines.

As an example, let's take a look at the website https://www.slidesharedown.net/. This website is a tool that allows users to download presentations from SlideShare, a platform for sharing presentations and slideshows. Some of the relevant keywords for this website might include "SlideShare download," "presentation download," "download slideshows," and so on.

It's important to note that these keywords should be used naturally throughout the website's content, including the page titles, meta descriptions, headers, and body text. This will help search engines understand what the website is about and improve its visibility in search results for relevant queries.