1. Used alone to mean something under discussion has been done and that there is no more to do. English = 'It's finished!', 'I'm done!', 'I've finished!', 'That's that, then!', 'All done!', and so on.
2. Used alone, often with an expression of surprise, to mean that something has been done and completed before the time that was expected. English = 'Already!?'