Odd "Suffix" at the end of URL

This is a site I am working on. Here is an example of a permalink to a specific article:

https://urbanfig.com/2012/05/garden-design-how-to-create-a-beautiful-green-space/#.T6jMs59Yu9K

I am wondering why the #.T6jMs59Yu9K is there, what purpose it serves, and how I can clean up the URL and get rid of it.

Any guidance would be so appreciated! Thank you!