When you want to have a website for your business on the Internet, you need to have it hosted on a server.
This website is accessible to the world for as long as this server is on. When the server is off people will not be able to access the website.
You could try to host this website on your own server but then you will have to keep in mind the electricity costs, buying costs of a server, maintenance and cooling. All this cost combined is much more than what you will have to pay to a web hosting service.
