The number of pages on a website depend on the content and function of the site, for example, if it's a business site, what does it need to show in terms of advertising your business?
We would expect most sites to have a home page, a page about the business, the products or services the business offers and a page for the clients or customers to contact the business for further details, or leave feedback or queries for the company and what they have to offer.
Other larger sites, such as an e-commerce site, may involve a database for information such as customer, product or transaction details.