Hi. Am new to use a GNSSR... Got a Garmin Nuvi 255W for the first time.
On the left half of the satellite signal status display, the outer circle shows a red dot.

What is that red dot representing ? The sun ?
The inner circle... is that the for the moon location ?

 

The inner circle is you.

 

Well, found the outer circle being the horizon; the inner circle a sky view at 45 degrees elevation, and the red dot the last heading calculated. The center point is the zenith.