You would say you "get off" the train. If you say you jumped off the train it sounds like you're literally jumping down from the train.

We "get on" and "get off" a train. I usually try to avoid saying "get", but in this case it is about the only way to say it. If you are getting off one train in order to get on another, you can say "I am switching trains". Another way to say "get on" is: "I am hopping on the train". I don't hear that much and maybe it's a bit dated (especially in the U.S. where people don't use trains much). If you said you were "jumping off", people would understand you and they wouldn't think you were intending to harm yourself, but I haven't heard it much. It's rather colorful though and I like it, so say it if you want.

You would normally get off the train. I hope you NEVER have to jump off a train! You would risk breaking your legs!

Unfortunately, it is very difficult to tell just from that piece. It couldean what you say, or it could be someone whose services, such as a mechanic etc, that the master uses regularly. As opposed to some other mechanic or serviceman.