Please forgive me, but I don't understand. I was going to schedule to come into an apple store and ask them to explain exactly what this means. Will I loose all my photos on my phone/desktop computer?

Photos is an application to manage your photos. It is storing your Photos in a Photos Library.

the Photos in your. Photos Library will not be affected by the shut-sown of My Photo stream.

Perhaps this user tip will help: I just wrote a bit of background information about My Photo Stream:

An Ubituary of My Photo Stream - Apple Community

I liked My Photo Stream very much, when it was new, but by now it has been replaced by iCloud Photos.

My Photo Stream was an old way that people used to automatically get pictures from their phone to their Mac. Not many people do that any more, which is why Apple is discontinuing it. With Photos, a "My Photo Stream" album would show up automatically in their album list. Now people use iCloud.com to synchronize pictures on their phone and Mac, so the old way is redundant and unnecessary.

If you haven't ever used My Photo Stream, like most people, then this doesn't affect you, at all. Don't worry about it!