υπηρεσίας is the word which means service. The meaning of the words include mesa or unimesa which means I need service please, or can I please get service which are the same thing.
Greek for "service" is υπηρεσία, pronounced as ypi̱resía. For instance, "car rental service" is "Υπηρεσία ενοικίασης αυτοκινήτων", pronounced as "Ypi̱resía enoikíasi̱s af̱tokiní̱to̱n".
The best word to learn for your trip is "parakalo," which is pronounced with a soft "para" and emphasis on the LO. There are several websites with phrases for travelers.
Para is the greek word for service. It's easy to say and pronounce. You can also make hand gestures for service that people would understand. Para is short of Parkalo.
