Learn Farsi: قبل از اینکه لغت جدیدی حفظ کنیم، باید تلفظ آن را تکرار کنیم. - Before we memorize a new word, we must repeat its pronunciation.

They are triggered by two different rules. The first one, hefz konim (we memorize), is in the subjunctive because it follows ghabl az inke (before). The second, tekrār konim (we repeat), follows bāyad (must). Both "before" and "must" introduce actions that are potential or required, rather than established facts, which is why Farsi uses the subjunctive here.

In loghat-e jadidi (a new word), why is the indefinite suffix -i attached to "new" instead of "word"?

When a noun is followed by an adjective in an ezafe chain (where the hidden "e" links them together), the indefinite -i (meaning "a" or "an") attaches to the very end of the whole phrase. So instead of putting it on the noun, it attaches to the adjective: loghat-e jadidi.

What are the dictionary forms (infinitives) of the verbs "memorize" and "repeat" used in this sentence?

Both are compound verbs that use kardan (to do). "To memorize" is hefz kardan, and "to repeat" is tekrār kardan. In this sentence, the non-verbal parts (hefz and tekrār) stay the same, while the kardan part changes to konim (the present subjunctive for "we").

Why do we need the word rā after talaffoz-e ān?

The word rā marks a direct object. Because (its pronunciation) is a specific, defined thing being acted upon by the verb "repeat," it requires the marker. Notice that in the first half of the sentence doesn't take because the makes it indefinite (a new word, not new word).