Learn Finnish: Voitko selittää, mikä ongelman syy on? - Can you explain what the reason for the problem is?

In a Finnish indirect question, the question word (here, mikä) must come first, right after the comma. After that, the rest of the clause usually follows a standard statement word order. Because the subject here is ongelman syy (the problem's reason), the verb on (is) naturally falls at the very end of the sentence.

Is the comma before "mikä" mandatory?

Yes! Unlike English, where you wouldn't put a comma before "what" in this sentence, Finnish punctuation rules require it. You must separate the main clause (Voitko selittää) from the indirect question clause (mikä ongelman syy on) with a comma.

Why does the Finnish sentence literally say "the problem's reason" instead of "reason for the problem"?

Finnish rarely uses prepositions like "for" to link two nouns together. Instead, it relies on the genitive case (possession) by adding -n. By changing ongelma (problem) to ongelman, you are literally saying "the problem's reason" (ongelman syy). This is the standard way to express "the reason for..." in Finnish.

Why use "mikä" instead of "mitä" for "what" here?