By format information, do you mean the underlying HTML / CSS code?  For HTML, you can view the page source.  The method may vary slightly for different browsers, but for Firefox, if you press the applications key pretty much anywhere on the page to bring up the context menu, choose "View page source".  That shows you the HTML.  The CSS that tells the browser how to display the various elements may be in the same file or may be in other files.  NVDA can read that, but whether the source itself for many pages is understandable is a different matter entirely *grin*.