As a Verb or Adjective:
1. Of an event, to happen and finish surprisingly quickly. English = (be) quick, (be) sudden.
1. Used alone as an expression of surprise that the time has passed unexpectedly quickly and that an event or experience is finished. English = 'Wow, that was quick!', 'Over already!?', 'Finished already?', 'Time flies!', 'The time has just flown!' and so on.
1. Used immediately next to a verb to mean the action happens and is finished with surprising and unexpected speed. English = quickly.
2. Used at the beginning (or end) of a sentence to mean the action or event described in the sentence happens and finishes with some surprise and speed. English = suddenly, all of a sudden, surprisingly quickly.