As many as it needs! The truth is, there is no hard and fast rule on how many pages your site should have.
The size of your site doesn’t really affect your site rankings. What is important is that your site provides relevant, high-quality original content. Whether your site has 10 pages or 100, make sure each page contains interesting, well-written information.
A good rule of thumb is to provide a page describing each service or product you offer. Also, remember that the search engines can penalize you if you steal content from other sites. Be sure all of your pages offer original content.
If you need help writing new website pages, contact us!