A business website is any website that’s devoted to representing a specific business. It should be branded like the business (the same logo and positioning) and communicate the types of products and/or services the business offers.
By now, every business out there should have a website. It’s a widespread expectation. Every potential customer you encounter will just assume that if they Google your business looking for more information, they’ll find a website. And if they don’t, it makes the business look less professional or legitimate.
E-commerce websites are business websites, but it’s also possible to have business websites that don’t sell anything directly, but rather encourage visitors to get in contact for more information (a lead generation website) or come to a storefront if they’re interested in becoming customers.