Breakdown of Bist du stolz auf die Fotos, die du machst?
sein
to be
du
you (informal singular)
machen
to make, to do
auf
on / to (down/up to a level)
Questions & Answers about Bist du stolz auf die Fotos, die du machst?
Why is the second die used here instead of just saying dass?
The second die is a relative pronoun meaning "that" or "which". You cannot use dass here because you are referring back to a specific noun, die Fotos. It takes the plural form to match Fotos, and the accusative case because the photos are the direct object of what you are making or taking in that second clause.
Why does the sentence use machst instead of a word for "take"?
In German, you don't "take" a picture, you "make" one! The correct set phrase is Fotos machen. If you used the verb nehmen (to take), it would sound like you are physically picking up a printed photograph off a table with your hands.
Why is it stolz auf? Doesn't auf mean "on"?
Prepositions rarely translate perfectly word-for-word between languages. In German, the adjective stolz (proud) always pairs with the preposition auf. It is highly recommended to memorize this combination together as stolz auf meaning "proud of".
Why does the verb machst come at the very end of the sentence?
The phrase die du machst is a relative clause. Relative clauses give more information about a noun (in this case, the photos) and they act like subordinate clauses. That means they always kick the conjugated verb, which is machst, to the very end of the clause.