Meaning of AH in English

aah [exclamation] - used to express understanding, pleasure, pain, surprise or the fact that you have noticed somethingAh yes, now I see what's wrong - the wires have come loose.Ah, it's wonderful to see you again.Ah, that's terrible, you must have been in such pain.Why has the train stopped? Ah, now we're off again.Ah, Jessica, I'm glad you could make it.

Cambridge English vocab.      Кембриджский английский словарь.