Брат и сестра редко перебивают друг друга.

Because the subject is Брат и сестра = brother and sister, which refers to two people.

In Russian, when two nouns are joined by и (and), the verb normally goes in the plural:

• Брат и сестра перебивают... = The brother and sister interrupt...
• so the verb is перебивают = they interrupt

Even though брат and сестра are each singular by themselves, together they form a plural subject.

Russian has no articles, so there is no direct equivalent of the or a/an.

So:

• брат can mean a brother or the brother
• сестра can mean a sister or the sister

The exact meaning depends on context. In this sentence, English might naturally translate it as Brother and sister rarely interrupt each other or The brother and sister rarely interrupt each other, depending on the situation.

They are in the nominative case, because they are the subject of the sentence — the people doing the action.

• брат = nominative singular
• сестра = nominative singular

That is the basic dictionary form for both words.

Редко means rarely.

In this sentence it comes before the verb:

• редко перебивают = rarely interrupt

This is a very natural word order in Russian. Russian word order is more flexible than English, but Брат и сестра редко перебивают друг друга sounds neutral and standard.

You could move редко in some contexts for emphasis, but this version is the most straightforward.

Перебивать means to interrupt, to cut someone off while they are speaking, or sometimes to talk over someone.

Here it is used in the sense of interrupting another person in conversation:

• перебивать кого-то = to interrupt someone

So:

• Брат и сестра редко перебивают друг друга = Brother and sister rarely interrupt each other

Перебивают is the imperfective present-tense form of перебивать.

That fits this sentence because the meaning is habitual or general:

• They rarely interrupt each other
  not
• They will interrupt each other

Russian often uses the imperfective for repeated, usual, or general actions.

Compare:

• перебивают = interrupt / are interrupting (imperfective)
• перебьют = will interrupt / interrupt once and finish the action (perfective future)

Since редко describes how often something happens, the imperfective is the natural choice.

The ending -ют in перебивают shows that this is 3rd person plural in the present tense.

The infinitive is перебивать.

Conjugation:

• я перебиваю = I interrupt
• ты перебиваешь = you interrupt
• он/она перебивает = he/she interrupts
• мы перебиваем = we interrupt
• вы перебиваете = you interrupt
• они перебивают = they interrupt

Since брат и сестра = they, the verb is перебивают.

Друг друга means each other or one another.

It is a very common Russian way to express a mutual action:

• они любят друг друга = they love each other
• они видят друг друга = they see each other
• они перебивают друг друга = they interrupt each other

So in your sentence, it shows that the action goes both ways: the brother interrupts the sister, and the sister interrupts the brother.

Because Russian expresses each other as a two-part phrase: друг друга.

You should learn it as a unit meaning each other, even though the individual words literally relate to friend or one another historically.

In modern usage, don’t translate it word-for-word. Just understand:

• друг друга = each other

This expression changes form depending on the grammar of the sentence.

Because the verb перебивать takes a direct object, and here each other is that object.

Russian says:

• перебивать кого? = interrupt whom?

That calls for the accusative case.

So the mutual expression appears here as:

• друг друга

This is the form commonly used after transitive verbs like любить, видеть, слышать, перебивать, and so on.

No. It changes depending on the case required by the verb or preposition.

Some common forms are:

• друг друга = each other (accusative/genitive-type form)
• друг другу = to each other
• друг другом = with each other
• друг о друге = about each other

Examples:

• Они любят друг друга. = They love each other.
• Они помогают друг другу. = They help each other.
• Они довольны друг другом. = They are pleased with each other.
• Они думают друг о друге. = They think about each other.

So in your sentence, друг друга is the right form because перебивать takes a direct object.

Yes — and that is probably the most natural interpretation.

Russian present tense often covers both:

• what is happening now
• what happens generally / habitually

With редко (rarely), the sentence is most naturally understood as a general habit:

• Brother and sister rarely interrupt each other

It describes the usual pattern of their behavior.

A natural stress pattern is:

Брат и сестра́ ре́дко перебива́ют друг дру́га.

Word stresses:

• брат — one syllable
• сестра́
• ре́дко
• перебива́ют
• друг дру́га

A rough pronunciation guide:

brat i syes-TRA RYED-ka pyerye-bi-VA-yut drook DROO-ga

The unstressed vowels are reduced in normal speech, so listening to native audio is especially helpful here.

Sometimes Russian can use X с Y to mean something like X and Y, but in this sentence Брат и сестра is the normal and straightforward choice.

Compare:

• Брат и сестра редко перебивают друг друга. = Brother and sister rarely interrupt each other.

If you said брат с сестрой, it might sound a little different in nuance, and it is not the most neutral version here. For a simple coordinated subject, и is best.

Yes, it is completely neutral and natural.

Nothing in it is especially formal, literary, slangy, or colloquial. It is a standard everyday Russian sentence:

• Брат и сестра = neutral nouns
• редко = neutral adverb
• перебивают = neutral verb
• друг друга = standard way to say each other

So this is a very good sentence for learning basic Russian grammar and vocabulary.