Sets ShowSecondsInSystemClock = 1 so the taskbar clock ticks seconds. Handy if you time things; costs a tiny amount of extra repaint. Takes effect on the next Explorer refresh. Reversible.
MaxTweaks applies this tweak with one click and snapshots your original setting first, so you can revert it cleanly at any time. A System Restore point is offered before batch changes, and every tweak links to its official source.
Get MaxTweaksOfficial documentation: https://learn.microsoft.com/en-us/windows/win32/shell/