A basic business Web site consists of one or more Web pages that contain (not surprisingly) just basic information about your business.
The point is to help people who are doing online search for a business like yours to find your business. Then they can contact you by phone or by e-mail, or see the map you so thoughtfully provided on your page.
A site like this is generally static, meaning it doesn't interact with the visitor and doesn't sell things directly to them, and -- good news -- doesn't require you to update it very often. Like a standing ad in the Yellow Pages of your telephone directory.
Let's say you offer consulting services. A consultant site is usually not much more than an elaborated resume that describe the consultant's areas of expertise, location, and contact info, along with work samples or pictures or links if that's relevant.
For a product site, you might add a list of your products, along with descriptions and maybe pictures, perhaps technical info or specs. You'd also explain how to order or how to contact a sales rep, or how to contact customer support by phone or email.
If your products are technical, you might add tech support info such as an FAQ (list of frequently-asked questions) and a tech-support phone number.
For a restaurant, add a menu, a map of your locations, your hours of operation, and a reservation phone number. For a retail store or a service such as a plumber or towing service or electrician, you can list services and perhaps prices.