On the Document information tab, you find information about the website you selected from the URLs window.
Title: Shows the title of the document.
Keywords: Lists all keywords of the document.
Description: Here you find a description of the website.
Robots: Indicates how the robots should index a website.
Number of frames: Shows how many frames are available.
Number of images: Shows how many images are included.
Document size: Displays the size of the document in bytes.
DMOZ category: Informs you about the category of the website.