Translation:János is singing and playing the violin in front of the tourists.
Having our answer marked as incorrect for using "János" instead of "John" seems silly for two reasons. First, you would almost always refer to someone by their actual name rather than the English equivalent, unless the named individual prefers otherwise or if they've anglicised it. I guess this statement can be rebutted because learning the Hungarian equivalent to English names (and vice versa) is an aim of the course. Second, there seems to be an inconsistency in the course - sometimes it's ok to leave the name as is (I could be wrong but I recall that Éva was fine to not translate to Eve) while for questions like this it isn't.