Learn Swedish: Vi diskuterar vad som gör graffitin kontroversiell. - We are discussing what makes the graffiti controversial.

In Swedish, when a question word like vad (what), vem (who), or vilken (which) acts as the subject of an indirect question, you must insert the particle som. In this sentence, vad is the subject because "what" is doing the action (making the graffiti controversial). If vad were the object, like in "We are discussing what we should do" (Vi diskuterar vad vi ska göra), you would not use som.

Could I use "får" instead of "gör" here for the word "makes"?

No, gör is the correct choice here because it is followed by an adjective (kontroversiell). You use göra when saying "make [someone/something] [adjective]", like "it makes me happy" (det gör mig glad). You use få when "make" means causing an action, which requires a verb, like "it makes me cry" (det får mig att gråta).

Why does "graffitin" end in "-n" instead of "-en"?

Graffiti is an en-word, but because it already ends in a vowel, it just takes an -n to become definite (graffitin). Swedish usually does this with loanwords ending in vowels to avoid awkward double-vowel endings like "graffitien".

Why is it "kontroversiell" and not "kontroversiellt"?