The short answer is the text from this post comes from a previous Google+ post. These hashtags are used to categorize what has been written. When clicked on, the reader is taken to other Google+ articles that have the same hashtags. It gives background information about the photo posted. The hashtag is created by the writer. The link is automatically generated by Google+. If the link does not work, one can put the hashtag into Google and come up with additional background information.
For example of hashtag use, when Trey Ratcliff had a photo walk in Austin, he suggested everyone use a certain hashtag on Google+ for their walk photos. If someone clicked on that particular hash tag or entered it in the Google+ search bar, one would see all the photowalk images even though they may have been posted in various places within Google+.
Some background information - Google+, up until now, is the only social media I posted to. I have been there since close to the beginning. Much effort was taken in posting there. My journalistic style is to give background on the image taken as well as how the image was taken for those interested in photography technical details. If a viewer wants info on the photo subject, it's there; how the image was taken, it's there or if someone just wants to quickly view the image and move on, that's okay too.
On trying other platforms to post to in order to replace Google+, I reuse my Google+ post for my now "new to me" social media platforms. No need to rewrite what I have already done once. Depending on the social media, sometime various links transfer and sometimes they do not. This is my way of allowing my Googe+ posts to live on when Google+ goes away.
It took years and years before I ever posted to social media. I think @treyratcliff is the one to suggest to his photographer pals to try Google+ out. I did and have enjoyed the Google+ photography community and met some very nice people. For this, I have to thank Trey!
Along with many getting pushed out of the Google+ nest, I'm trying to find a new photographic home. Posting is something I am not naturally inclined to do. However, I am very appreciative of anyone responding to a post. ;-)