Если ты ошибёшься, сотри слово ластиком и напиши заголовок ещё раз.

Ошибёшься is the 2nd person singular future form of ошибиться, which means to make a mistake.

Breakdown:

• ошибиться = perfective infinitive
• ты ошибёшься = you will make a mistake

In this sentence, it appears after если and means if you make a mistake.

A very important point for learners: in Russian, when talking about a future condition, Russian often uses a future form where English uses the present:

• Russian: Если ты ошибёшься...
• English: If you make a mistake...

So even though ошибёшься is literally future, the natural English translation is still if you make a mistake, not if you will make a mistake.

Yes, -ся is the reflexive particle, but here it does not mean something like you mistake yourself in a literal sense.

The verb is simply ошибиться / ошибаться, and this verb means to be mistaken / to make a mistake. For many Russian verbs, the reflexive ending is just part of the normal dictionary form and should be learned with the verb.

So:

• ошибиться = to make a mistake once, to be mistaken
• ошибаться = to make mistakes, to be mistaken repeatedly/in general

In this sentence, ошибёшься comes from ошибиться, the perfective verb.

Russian uses the perfective here because the sentence refers to a single completed mistake in the future.

Compare:

• Если ты ошибёшься... = If you make a mistake... / If you happen to make a mistake...
• Если ты ошибаешься... = If you are mistaken... / If you are making mistakes...

So the perfective verb ошибиться fits the idea of one mistake happening, which then triggers the instruction to erase and rewrite.

They are both imperatives: command forms.

• сотри = erase
• напиши = write

More specifically, they are perfective imperatives. In Russian, perfective imperatives are very common when you tell someone to do a single complete action.

Here the speaker means:

1. erase the word,
2. write the heading again.

So perfective makes sense:

• сотри = erase it completely
• напиши = write it out

If you used imperfective imperatives instead, the meaning could sound more like a general instruction about process, repetition, or manner.

Because Russian imperative forms are often not fully predictable from the infinitive unless you already know the verb pattern.

Here:

• infinitive: стереть = to erase
• imperative: сотри = erase!

This is a normal imperative form of that verb, even though it looks quite different from the infinitive.

So this is something worth memorizing:

• стереть → сотри
• написать → напиши

Слово is in the accusative case, because it is the direct object of сотри.

However, for many inanimate nouns, the accusative looks exactly like the nominative. Since слово is a neuter inanimate noun, its accusative singular is the same as its nominative singular:

• nominative: слово
• accusative: слово

So the form does not change, even though the case has changed.

Ластиком is instrumental because it expresses the tool used to do the action.

• ластик = eraser
• ластиком = with an eraser

This is a very common use of the instrumental case in Russian:

• писать ручкой = to write with a pen
• резать ножом = to cut with a knife
• стереть ластиком = to erase with an eraser

So Сотри слово ластиком literally means Erase the word with an eraser.

Заголовок is also in the accusative case, because it is the direct object of напиши.

Just like слово, it is inanimate, so in the singular its accusative looks like the nominative:

• nominative: заголовок
• accusative: заголовок

So the form stays the same.

Заголовок usually means title, heading, or headline, depending on context.

Possible translations include:

• title
• heading
• headline

In a classroom or workbook context, heading or title is probably the best choice.

So напиши заголовок ещё раз means something like:

• write the heading again
• rewrite the title

Ещё раз means again or one more time.

Literally:

• ещё = more / still / yet
• раз = time / occasion

Together:

• ещё раз = one more time, again

So:

• напиши заголовок ещё раз = write the heading again

This is a very common expression in Russian:

• Скажи ещё раз. = Say it again.
• Повтори ещё раз. = Repeat it one more time.

Because Если ты ошибёшься is a subordinate clause introduced by если (if), and in Russian such clauses are normally separated by a comma from the main clause.

So the structure is:

• Если ты ошибёшься, = if you make a mistake,
• сотри слово ластиком и напиши заголовок ещё раз. = erase the word with an eraser and write the heading again.

Russian punctuation is stricter than English in this area: the comma is required here.

No, ты is not strictly necessary, because the verb form ошибёшься already tells you that the subject is you singular.

So both are possible:

• Если ты ошибёшься, ...
• Если ошибёшься, ...

The version with ты can sound a bit more direct, clear, or conversational. In instructions aimed at one person, including ты is perfectly natural.

Russian has no articles like a/an/the.

That means nouns such as слово and заголовок do not need a separate word to show definiteness. Russian leaves that to context.

So:

• сотри слово can mean erase the word
• напиши заголовок can mean write the heading/title

The exact English article depends on the situation, not on a separate Russian word.

Yes. Russian word order is more flexible than English, although the given order is natural and clear.

The sentence as written:

• Если ты ошибёшься, сотри слово ластиком и напиши заголовок ещё раз.

This is a neutral instruction.

You could move things around for emphasis, for example:

• Если ты ошибёшься, ластиком сотри слово...
• Если ты ошибёшься, заголовок напиши ещё раз.

But those versions sound more marked or emphatic. The original is the most straightforward for a basic instruction.

И simply means and, linking two commands:

1. сотри слово ластиком
2. напиши заголовок ещё раз

In context, it often has the sense of and then:

• erase the word,
• and then write the heading again.

So the sequence is understood naturally even though Russian just uses и.

Yes, especially for a learner.

Useful stress points in this sentence include:

• ошибёшься — the ё is always stressed
• сотри́
• ла́стиком
• напиши́
• заголо́вок
• ещё

Stress in Russian can change from word to word and is not always predictable, so it is worth learning stressed forms when possible.

Also remember:

• ё is very helpful because it always shows the stressed syllable.