What does it mean that a ○ appears in the notification bar of mobile phone?

This point is the weather in the notification bar of the application "Weather Link".

You can multi-touch the weather interface, slide the screen up and down, and find the notification bar to remind you. After entering, close the notice bar and the weather dot will disappear.

The notification bar of the mobile phone is set on the system setting page of the mobile phone. Generally, you need to click the notification option to set it, so that you can set the notification method. Android phones and Apple phones are set in the same way.