A typical static website will contain pages only. When referring to a site in Sharepoint, what we really mean are the pages along with the lists and libraries, security and other settings. A site can have subsites, which will inherit these features.
A site is part of a site collection. A site collection is a branching collection of sites with one site at the root. The root site will contain attributes that are common to all subsites, such as some search settings and a Recycle Bin for deleted items.