Pinterest introduced today its brand new web analytics which allows you to see how many people have pinned content from your site, repins, the reach of your content, and more. The export feature allows you to download a file with all of the data from the site metrics page.
In order to take advantage of this feature you need to have a verified website and have switched to Pinterest's new look. If you have a website listed on your profile with a check mark next to it you're already verified. If you do not see a check mark please follow these steps to verify your site.
Once your site has been verified the analytics feature is available from the top right menu.
For more information on Pinterest's analytics and how to use them, Pinterest has created a walkthrough video.