Learn Farsi: مرجان‌ها به جلبک نیاز دارند، از این رو باید از آنها محافظت کنیم. - Corals need algae; hence, we must protect them.

az in ru literally translates to "from this face" or "from this direction," meaning "for this reason" or "hence." It connects two independent clauses to show a logical consequence. While it means the same thing as pas (so) or banābarin (therefore), it elevates your Farsi because it is much more formal and often used in writing or educated speech.

Why do we see the preposition be before jolbak and az before ānhā?

In Farsi, compound verbs are strictly paired with specific prepositions. To express needing something, you use be ... niyāz dāštan (literally "to have a need to"). To express protecting something, you use az ... mohāfezat kardan (literally "to do protection from"). As a B2 learner, memorizing these preposition-verb pairs is crucial because they rarely translate word-for-word to English.

Why is the verb mohāfezat konim in the subjunctive mood here?

The subjunctive is triggered by the modal word bāyad (must). The connector az in ru starts a new independent clause, and the rules of that clause operate normally: since we are saying we must protect them, bāyad requires the following verb to take the subjunctive form.

The subject marjān-hā (corals) is not human, so why does it take the plural verb dārand?

While inanimate plural nouns typically take a singular verb in Farsi, biological entities like animals and plants often act as exceptions. In formal, scientific, or nature-related contexts, living organisms are frequently treated as animate and will take a plural verb to match their plural marker.