This is yet another new difficult thing in German. "dran" is not a noun and therefore this phrase is really confusing. "du bist dran" sounds like "du bist krank". I want to say that if it is your turn then in German it is considered as some kind of state that you are staying in until it is not your turn any more.
complicated. normally questions in German are started either with a verb or with a questionword. if you wanted to know whether it is my turn you would say 'Bist du jetzt dran?'. If i told you first 'ich bin dran' and you wanted to question me and my right you would ask 'Ach DU bist jetzt dran?'
No, "dran" does not mean "next", that is "nächst".
"Dran" in isolation is short for "daran", which has many meanings in itself
And here you're dealing with the set phrase "dran sein"
English is actually rife with this kind of sayings that don't make any logical sense, but are shared by part or all of the English speaking world ☺