Watch Face Graphic Meaning

It shows where the sun is in account with the horizon before sets. For example, when the bar is full it's noon.

I don't think it is either Steps or Sun/Horizon.  I took a couple more screenshots 50 minutes apart after taking a ~mile walk.  The graphic hasn't moved.  In fact, it hasn't moved at all this morning.  The only other item that seems to match the progress bar (graphic) is my Body Battery.  It has held steady around 90% this morning which seems close to the progress bar's value.  Come on Garmin.  This is a standard watch face and I can't find any documentation.

I'm using that watchface but with other data fields since most of what you got there are not interesting to me and use extra battery like seconds, weather and pulse. My data fields are date and month at top, number of notifications and battery level at the bottom. And the step goal bar since it can't be removed.

The sun and time is the sunset time. The sun will set at 19:07. After sunset it will be switched to the sunrise time.

The smiley bar below is the number of steps. The full bar is your goal. It is strange that it didn't move after a mile walk, but that could be some other issue. What is your daily step goal and how many steps have you taken? Now it looks like about 15% of the goal.

It looks to me to indicate sunset it's at 7:08PM. Once the sun sets, you'll likely get an up arrow over the sun and a new time to the right to indicate sunrise.

It may be intensity minutes. Try a fast run and report back to be sure

You'd think it was the step progress bar.... but it might be linked to the data field chosen... In this case it would seem it could be linked to the sunset /sunrise datafield..or the heart rate datafield. It would be interesting to know the answer. : -) 

I've watched this for a few days, and it does seem to be a step tracker.