Frontpage is a component that is part of the core of Joomla!, like the front page of a newspaper, it shows (usually) multiple pieces of content arranged in some way.
When you install Joomla! the front page component is by default set as the homepage of your site (that is it is the first link on your Main Menu) but front page does not have to be your "home" page.
What exactly appears on the front page and how it is laid out is controlled in two ways. First, if you open the menu link in your menu manager in the back end there are numerous parameters that control the number of items shown, the number of columns etc.
To control which items are shown you must also indicate that an item should be placed on the front page by editing the parameters for the content item. In the back end this will be indicated by an icon in the front page column of the list of content items/articles.
In addition, you can use the front page manager (in the content menu of the backend) to control the publication dates and other variables for content items that are on the front page.