Во-первых, нужно подготовить интервью.

Во-первых means first, firstly, or to begin with when you are listing points.

• во-первых = first / firstly
• often followed later by во-вторых = secondly

It is written with a hyphen because that is the standard spelling of this fixed expression in Russian.

It is followed by a comma because it functions as an introductory word or phrase. Introductory elements like this are usually set off by commas:

• Во-первых, нужно подготовить интервью.
• Во-вторых, нужно проверить вопросы.

Нужно is an impersonal word meaning it is necessary, one needs to, or it’s necessary to.

In this sentence, there is no specific subject like I, you, or we. Russian often uses this kind of impersonal structure:

• Нужно подготовить интервью. = It is necessary to prepare the interview.

So grammatically, нужно sets up the idea of necessity, and the infinitive подготовить tells you what needs to be done.

Because after нужно, Russian normally uses the infinitive.

So the pattern is:

• нужно + infinitive

Examples:

• Нужно читать. = It’s necessary to read.
• Нужно уйти. = It’s necessary to leave.
• Нужно подготовить интервью. = It’s necessary to prepare the interview.

If you used a conjugated verb, the meaning would change:

• Подготовим интервью. = We will prepare the interview.
• Подготовьте интервью. = Prepare the interview. / Please prepare the interview.

Подготовить is perfective, so it focuses on the result: the interview should end up prepared.

That fits well with нужно, because the sentence is about what must be accomplished.

• нужно подготовить интервью = the interview needs to be prepared, brought to a ready state

Compare:

• подготовить = to prepare, to get something prepared completely
• подготавливать = to be preparing / to prepare repeatedly or as a process
• готовить = to prepare, but often broader and less specifically to get fully ready

In many situations, подготовить is the most natural choice when you mean a concrete task with a desired outcome.

It is the direct object of подготовить, so logically it is in the accusative.

However, интервью is a borrowed noun that is usually indeclinable in Russian. That means its form does not change across cases.

So:

• nominative: интервью
• accusative: интервью
• genitive: интервью
• etc.

The case is determined by its role in the sentence, not by a visible ending.

Интервью is usually treated as neuter in Russian.

You can see this in agreement:

• интересное интервью = an interesting interview
• новое интервью = a new interview

Even though the word does not change its ending, adjectives agreeing with it will show the gender and case.

The sentence leaves that unspecified on purpose.

Russian often uses impersonal constructions when the important idea is the action itself, not who performs it.

So:

• Нужно подготовить интервью. = It’s necessary to prepare the interview.

Depending on context, English might translate this as:

• We need to prepare the interview.
• You need to prepare the interview.
• The interview needs to be prepared.

Russian does not always state the subject when it can be understood from context or when it is not important.

Yes. In many everyday contexts, надо and нужно are very close.

• Нужно подготовить интервью.
• Надо подготовить интервью.

Both mean something like it is necessary to prepare the interview.

A rough tendency:

• надо often sounds a bit more conversational
• нужно can sound slightly more neutral or formal

But in many situations, they are interchangeable.

The sentence is natural as written, but Russian word order is more flexible than English word order.

Neutral version:

• Во-первых, нужно подготовить интервью.

Other possible versions:

• Во-первых, интервью нужно подготовить.
• Нужно, во-первых, подготовить интервью.

These alternatives may shift the emphasis slightly. For example:

• интервью нужно подготовить can emphasize the interview as the thing that needs preparation

The original version is a very normal, neutral way to say it.

The main stresses are:

• во-пЕрвых
• нУжно
• подготОвить
• интервьЮ

A simple pronunciation guide:

• Во-первых ≈ va-PER-vykh
• нужно ≈ NOOZH-na
• подготовить ≈ pad-ga-TO-vitʹ
• интервью ≈ een-ter-VYU

The final -ю in интервью is stressed.

Russian has no articles, so nouns appear without words like a or the.

That means интервью by itself could correspond to:

• the interview
• an interview

The context tells you which one is meant.

In a sentence like this, English often uses the interview if both speakers already know which interview they are talking about. But Russian does not need to mark that explicitly.