The context of one article is set in the page which displays this article.
One article linked to many pages has as much "context" as it has parent pages.
Editing the context will set:
An article "view" will set its look inside one page.
The available views list depends on your website and was defined by your webdesigner.
The "type" of one article is usually used to set its position on one page.
For example, one article with the type "side_bar" will be displayed in the side bar of the parent page.
Types are created by the developer when he creates the website and normally they shouldn't change during your website live.