Kizy doesn't use GPS. Instead, it uses Cell Phones antennae and WiFi to localize. This is a tradeoff between precision on side, and low power and coverage on the other side.
If WiFi are visible, no matter if they are encrypted or not, the system will use their identification to improve accuracy. If no WiFi is visible, it will use the cell phone antenna to localize. This leads to different levels of precision.
The red circle is meant to show these levels of precision, aiming to have 95% of the data within this circle. Note that the minimum precision item displayed is 40m, so if the system calculates a better precision than 40m, it will show 40m range.
The size of the circle is visible in the export data in the field "range".