What does 'time left' and 'grace left' mean?
When it's your turn to move, you get a certain amount of time to make your move (for example 24 hours). This is the 'time left' indicated. As long as you make your move before 'time left' reaches '00:00', you're fine.
Every player also gets a certain amount of 'grace time'. As soon as your 'time left' reaches '00:00', you start to lose 'grace time'. If you don't make a move before your 'grace left' reaches '00:00' you will lose the game. But if you make a move before that, on your next turn first you get the normal 'time left' amount again. Only when this is used up, the grace time is counting down again.
If you need more time, you can request one or more vacation days.