What exactly do interns in travel companies do?

Do odd jobs, print and copy, answer the phone, run errands, send tickets to guests, get tickets, and pick up the station for free when the tour guide is in short supply, clean up and kiss up. That's basically it. There's no salary. You can practice with the old guide car if you have the opportunity, but you must come. Help the tour guide find someone to buy food and drink for the tour guide, otherwise many tour guides will not talk about anything useful in the car, and you will not learn anything.