Cloud widget?

I am totally new to this, so sorry for the entry level question.
I am currently playing around with building my first site. I added the cloud widget to the sidebar on my blog page.
I can’t figure out what it’s for, how to use it, or whether it even applies to my site.
When I try to research it I get pages on Apple’s iCloud….
http://qrbrochure.info/blog-2/

Thanks,
Annette