Translation:I'm sorry, I have an appointment.
I was asking the same to myself too. Where's the context of this sentence? Or is this just some sort of pleasantry.
'I'm sorry, I have a meeting' was rejected and corrected to 'date'...
a) 'meeting' and 'appointment' are mostly interchangeable
b) there is no context that would specify, whether we are talking about meeting/appointment or a date
i put "pardon me" and it said i had to put "excuse me" which i would usually have put but that translation feels slightly off