We might divide a page template into a header, content, sidebar and footer where these are in separate files. The content will change most between pages, so rather than having a content file, we include the content into a page file which pulls in the individual template files and defines the unique features of that page. The unique features of a page will be the title, description and article content. We can define these at the start of the page template with say PHP code to set the value of variables that are used by the other templates such as the header template. Then we assemble the page by including the required templates and inserting the content.
I would say the number one benefit to website templates is that they‘re going to save you from having to wait for somebody else to get done with your website. You won‘t control don‘t you? Well website templates allow you to have a personal website set up within a few days after purchasing. All you would need is to select the platform you want and then choose templates that are going to suit it. Now compare this to trying to do everything yourself or hiring a professional web developer. It can take days before the product is even ready to get started.