The (A?) translator isn't here.

[Marika33]

Could you please explain to me why she uses a definite article in this case?
Is she talking about some specific translator (someone both of them know, or have mentioned previously) or any translator at all (that hasn't been mentioned before) = one of many?

Source (a small YouTube short)

 

[tedmc]

She is probably referring to someone in the restaurant who usually does translation for the waiters.

 

[jutfrank]

Yes, she's referring to a member of staff. Yes, the waiter very likely knows this person since he or she works with them, and no, the customer probably doesn't.

The word 'the' is used to make reference to the translator. You can understand there to be an implication that there is only one translator who works there, or who is working there at the relevant time. She could have also referred to 'the chef', 'the manager', or 'the owner', if there were also only one of each.