Если я буду долго ждать на остановке без шарфа, я замёрзну.

Если means if and introduces a condition.

So the sentence has this basic structure:

• Если
  • condition
• result

In this sentence:

• Если я буду долго ждать на остановке без шарфа = if I wait for a long time at the bus stop without a scarf
• я замёрзну = I will get cold / freeze

Russian uses a comma between these two parts, just like in English when the if-clause comes first.

Russian normally puts a comma between the if-clause and the main clause:

• Если ..., ...

So:

• Если я буду долго ждать на остановке без шарфа, я замёрзну.

This is standard punctuation in Russian.

Буду ждать is the future tense of the imperfective verb ждать.

Russian forms the future of imperfective verbs like this:

• буду / будешь / будет / будем / будете / будут
  • infinitive

So:

• ждать = to wait
• буду ждать = I will be waiting / I will wait

You cannot use жду here, because жду is present tense: I am waiting.

That is a very common question. Russian and English work differently here.

In English, after if, we normally use the present tense for future meaning:

• If I wait too long, I’ll get cold.

In Russian, it is normal to use the actual future tense if the meaning is future:

• Если я буду долго ждать..., я замёрзну.

So this is one of those places where you should not copy English grammar directly.

Because the sentence focuses on the process/duration of waiting, not on completing the action.

• ждать = imperfective, ongoing process
• подождать = perfective, wait for a while / complete a waiting action

Here, буду долго ждать means I’ll be waiting for a long time, which fits the idea of duration very naturally.

Долго means for a long time.

It modifies ждать:

• буду долго ждать = will wait for a long time

Its position is flexible, but this is the most natural order here. Russian word order can move around more than English, but буду долго ждать sounds neutral and natural.

It is the prepositional case after на when на means at/on a location.

• остановка = stop
• на остановке = at the stop

So:

• на остановке = at the bus stop / at the stop

This is a location phrase, so на + prepositional is expected.

Most often, yes, in everyday speech it means a stop for public transport, especially a bus stop.

Depending on context, it can also be a tram stop or similar. In this sentence, на остановке is naturally understood as at the bus stop or at the transit stop.

Because без always takes the genitive case.

The noun is шарф = scarf.
Its genitive singular form is шарфа.

So:

• без
  • genitive
• без шарфа = without a scarf

This is a very important pattern to remember:

• без сахара = without sugar
• без машины = without a car
• без шарфа = without a scarf

Because замёрзну is a perfective future and expresses the result: I’ll get cold / I’ll freeze.

Compare:

• мёрзнуть = to be cold, to feel cold, to be freezing
• замёрзнуть = to become cold, to freeze, to end up freezing

In this sentence, the meaning is not just I will be feeling cold, but if I wait too long, the result will be that I get cold. That is why замёрзну fits very well.

This is mainly an aspect and meaning difference.

• мёрзнуть = imperfective
  Focus on the state/process: being cold, freezing
• замёрзнуть = perfective
  Focus on reaching the result: getting cold, freezing

Examples:

• Я мёрзну. = I’m cold / I’m freezing.
• Я замёрзну. = I’ll get cold / I’ll freeze.

So in your sentence:

• waiting is the ongoing process: буду ждать
• freezing is the resulting event: замёрзну

Russian often repeats the subject for clarity, especially when there are two clauses:

• Если я буду долго ждать..., я замёрзну.

This is perfectly natural. In some contexts, Russian can omit the second я if the subject is obvious, but keeping it sounds clear and standard.

So the repeated я is not strange or unnecessary.

The word order can change, because Russian is fairly flexible.

The version you have is the most neutral:

• Если я буду долго ждать на остановке без шарфа, я замёрзну.

You could also move some parts for emphasis, for example:

• Если я буду ждать на остановке долго без шарфа, я замёрзну.
• Я замёрзну, если буду долго ждать на остановке без шарфа.

But the original order is the most natural for a basic statement.

Yes, ё is important here.

• замёрзну is pronounced with yo: za-MYORZ-nu
• the stress falls on ё

Even though ё is sometimes written as е in ordinary texts, learners should remember that the real pronunciation is with ё.

So:

• written carefully: замёрзну
• often written in less careful texts: замерзну
• but still pronounced zamyorznu

Yes, you can. Both are grammatical.

• если я буду долго ждать
• если я долго буду ждать

The first one is more neutral and common in teaching materials. The second may sound slightly more marked, depending on context, because долго gets a bit more prominence.

For a learner, буду долго ждать is a very good default pattern.