I made the same mistake. From my knowledge of Mandarin, I assume the word "bạn" in Vietnamese came from the Chinese word 伴 bàn which means companion or partner. So I can understand why it can mean both "you" and "friend."
I just speak about as much Vietnamese as I know from up this lesson, but looking at Wiktionary and from my knowledge of other languages where pronouns make an open class, the first meaning of bạn is friend. When used as 'you', what one is really saying is calling the interlocutor a friend.
Why does drop down hint deceive us with "you"? That's what I put and it was wrong. "Friends" makes more sense but with so many goofy sentences how do we switch gears?
The hints are supposed to give a clef over a word itself, but not always give the matched translation for the whole sentence. Then, the words you and friend should appear in the hints together in every sentence with the Vietnamese bạn. The user could select the English word that is needed for the translation and pick the correct from the hints if necessary. ;)