Questions & Answers about من هذا الأخ؟
Why do we use من instead of ما in this sentence?
من (man) means 'who' and is used only for people. Since we are asking about a brother (a person), we must use من. If we were asking 'what is this?' about an object, we would use ما (maa).
I don't see a word for 'is'. How does the sentence mean 'Who IS this brother?'
In Arabic, there is no word for 'is' or 'are' in the present tense. You simply put the question word and the subject together. So, 'Who this brother?' naturally translates to 'Who is this brother?' in English.
Why does the word for brother (الأخ) have the 'al-' (the) prefix here?
In Arabic, when you want to say 'this [noun]', the noun must be definite, meaning it needs the 'al-' (the) prefix. So, 'this brother' is literally phrased as 'this the-brother' (هذا الأخ).
What would happen if I left the 'al-' off and just said من هذا أخ?
Without the definite article 'al-', هذا أخ forms a complete sentence meaning 'This is a brother.' The question would then awkwardly mean 'Who is "this is a brother"?' which doesn't make sense! Always use 'al-' after هذا when pointing out a specific person or thing.