This plugin is used to disable the copy the content from your website. Hence, no one can copy content from your blog.
This plugin has used special algorithm that prevents copying by making the selected text that is targeted to be copied, to disappear! The only way to recover is to reload the page in the web browser. If they try again the content disappears again.
As long as they keep trying to select and copy your content the content will disappear before they can get a chance to execute the copy command!