It copies it to a temporary space called the "Clipboard" from which you can paste it to another location, e.g., an email.
Be aware that the "clipboard" is overwritten if you copy something else to it.
Also note that copied text from copyrighted books will have text appended to it giving the Source of the material and a link to the book entry in Tunes.
I'm not aware of a way to directly see the clipboard. If something is "copied" to clipboard, you can then "paste" it to an app that accepts this such as a text editor. If you don't need the chart in full resolution, you can just take a screen shot of it by briefly pressing the home and start buttons at the same time. The pic will be saved to the Photos app.