[RajatPawar]

pawn Код:

SetTimer("Finsh",300000,false);

forward Finsh();
public Finsh()
{
new string[ 41 ];
format( string, sizeof(string), "~g~PRASOME PALAUKTI, KEICIAMA ~w~MISIJA");
GameTextForAll( string, 6000, 0 );
SendRconCommand("changemode armijosm");
return 1;
}

You aren't using 'playerid' as a param in the function, so you don't need it, also to set a player specific timer, you need to use SetTimerEx, not SetTimer.