Learn Arabic (Modern Standard): هذه مقارنة مفيدة. أما الهاتف الجديد فهو أنيق. - This is a useful comparison. As for the new phone, it is elegant.

This is the second half of the أما ... فـ (as for ... then) structure. Whenever you introduce a new topic with أما, the actual comment or statement about that topic must be introduced by the prefix فـ.

Why do we need the pronoun هو in فهو أنيق? Couldn't we just attach the prefix and say فأنيق?

While it is grammatically possible to attach the فـ directly to the adjective, inserting the matching pronoun هو (it/he) is the standard and most natural way to structure this in Arabic. It acts as a clear bridge separating the topic from its predicate.

Why doesn't the word أنيق take the definite article الـ like الهاتف and الجديد do?

Because it is the predicate of the sentence, providing the meaning "is elegant". If you added الـ to it, the phrase would become an incomplete fragment meaning "the elegant new phone". Keeping it indefinite is what creates the invisible "is" in an Arabic nominal sentence.

Why do we use the feminine word هذه to point to مقارنة?

In Arabic, abstract concepts have grammatical gender just like physical objects. The word مقارنة (comparison) ends with the feminine marker taa marbuta, so we must use the feminine demonstrative pronoun هذه (this) to match it.