It shows on the right border of the current screen and updates as time elapses.
The default period is 5 minutes. Use CTRL + MOUSE_WHEEL_UP to add a minute, CTRL + MOUSE_WHEEL_DOWN to reduce by a minute. Use CTRL + LEFT_DOUBLE_CLICK to reset.
Hit ESCAPE to exit.
Make sure to fetch fresh releases here: https://github.com/diresi/wimer/releases
I intend to use this in (online) meetings when sharing my desktop. Folks will see their speaking time pass and - hopefully - finish soon enough.