lool this is easy to explain ;-)...
It shows you the server up time. Whom it is a 32bit server, this value is important.
The function GetTickCount use a DWORD (32bit), if you reach the time limit (49.7 days) the value starts from begin (0).
In this time all timing function in your server get problems (the game server use many of them).
So the Red mean : remember to reboot your server system ;-)