Your tracker has two different ways to get its location.
1- The tracker always tries to locate itself first with a GPS satellite fix. A tracking fix from a satellite is always the most accurate way for the tracker to know where it is.
2- If the tracker can't get a satellite fix, it will try to use a cell tower fix. This is less accurate than a GPS fix but can still be helpful for understanding where your tracker is.
Cell tower fixes are always reported inside of a light blue circle. The circle indicates the margin of error (in other words, the tracker is somewhere in the blue circle).
You might see a cell tower fix if your tracker is inside a building or placed in a spot where it can't hear a GPS satellite. You tend to see cell tower fixes less frequently when the tracker is outdoors or in a car.
Too long; didn't read:
If your tracker reports a weird address, it's using a cell tower because it can't find a GPS satellite. Move it somewhere with a better view of the sky.
The blue circle always indicates a cell tower fix.