Okay, when 제비꽃, 바이올렛 says,"What is a week-end?", I don't get it. What's so funny about it?

Well, some people who don't know the show so well don't understand that for the Crawley family work doesn't exist. 일 in, 일 out, is the same. Saturday is no different to Thursday, Monday is no different to Sunday. They don't work, none of them go to school, so every 일 for them is like a holiday for us normal people :D The middle class Crawleys who arrive at Downton in series one work, and Matthew has a job, so he works weekdays and has weekends off. So, pretty much, when Robert insists on him not having a job, he says he will have plenty of time on afternoons and weekends, and Violet, the dowager countess, granny, whatever 당신 want to call her, doesn't know what a weekend is, and there is this look of surprise from Matthew as he realises that he is in a very different place now, among a very different class than he is used to. Hope this helped :) Thanks :D

Well it's just....she doesn't know what a weekend is because she never worked in her whole life! Everyday is the same, she can't imagine a "simple" life.