Дети боялись ведьмы.

Дети means children and is the normal plural form of ребёнок (child).

A few important points:

• Singular: ребёнок = child
• Plural: дети = children

This is an irregular plural, much like English child → children.
You would not say ребёнки in standard Russian for children.

Боялись is past tense.

It comes from the verb бояться = to be afraid.

Why it means they were afraid:

• -л- is a sign of the past tense in Russian
• -и shows the subject is plural

So:

• я боялся / боялась = I was afraid
• он боялся = he was afraid
• она боялась = she was afraid
• они боялись = they were afraid

Here the subject is дети, so боялись means the children were afraid.

The -сь is the reflexive particle, a short form of -ся.

The dictionary form is:

• бояться = to be afraid

In Russian, this verb is simply learned as a whole verb: бояться.
So in the past plural, it becomes:

• боялись

This -ся / -сь is part of the verb, not a separate word.
You should think of бояться as the standard Russian way to say to be afraid.

Because the verb бояться takes the genitive case, not the accusative.

So:

• бояться кого? чего? = to be afraid of whom? of what?

With ведьма (witch), the genitive singular is:

• ведьма → ведьмы

That is why the sentence is:

• Дети боялись ведьмы.

not:

• Дети боялись ведьму.

This is something you mainly have to memorize with the verb бояться: it governs the genitive.

Good question, because ведьмы can look ambiguous when taken by itself.

Forms of ведьма are:

• nominative singular: ведьма
• genitive singular: ведьмы
• nominative plural: ведьмы
• accusative plural (for this noun): ведьм

So ведьмы could mean either:

• of the witch (genitive singular), or
• witches (nominative plural)

But in this sentence, the verb бояться requires the genitive, so ведьмы must be genitive singular.

If you wanted to say The children were afraid of witches, you would say:

• Дети боялись ведьм.

It can mean either, depending on context.

Russian has no articles like a/an/the, so:

• ведьмы here can mean of a witch
• or of the witch

Context tells you which one is meant.

So Дети боялись ведьмы could be translated as:

• The children were afraid of a witch
• The children were afraid of the witch

The basic order here is:

• Дети = subject
• боялись = verb
• ведьмы = object

So it is basically Subject–Verb–Object, which feels familiar to English speakers.

Russian word order is more flexible than English, though. You could change it for emphasis, for example:

• Ведьмы боялись дети.
• Боялись дети ведьмы.

But these sound marked or literary and would be used only in a special context.
The most natural neutral version is:

• Дети боялись ведьмы.

Бояться is imperfective.

That matters because it describes a state or ongoing feeling, not a single completed event.

So Дети боялись ведьмы means something like:

• The children were afraid of the witch
• The children used to fear the witch

It presents fear as a condition, not as a sudden moment of becoming frightened.

If you want a more single-event idea like got scared, Russian often uses a different verb, for example:

• Дети испугались ведьмы. = The children got scared of the witch.

So:

• боялись = were afraid / feared
• испугались = got frightened

The usual stress is:

• Де́ти боя́лись ведьмы

A rough pronunciation guide:

• Де́ти ≈ DYE-ti
• боя́лись ≈ ba-YA-lis’
• ве́дьмы ≈ VYED’-mɨ

A more careful approximation:

• [ˈdʲetʲɪ bɐˈjalʲɪsʲ ˈvʲedʲmɨ]

For a learner, the most useful thing is just to remember the stressed syllables:

• ДЕ́ти
• боЯ́лись
• ВЕ́дьмы

Not normally, no.

Because ведьмы here is interpreted as genitive singular after бояться, the sentence most naturally means:

• The children were afraid of a witch
• The children were afraid of the witch

If you want the general plural witches, you would usually say:

• Дети боялись ведьм.

That clearly means:

• The children were afraid of witches.

Дети is in the nominative case, because it is the subject of the sentence.

So the structure is:

• Дети — nominative plural subject
• боялись — past tense plural verb
• ведьмы — genitive singular object

This is a very common pattern in Russian: the subject is nominative, while the object may be in another case depending on the verb.

In the past tense, Russian verbs agree with the subject in:

• gender if the subject is singular
• number if the subject is plural

So with singular subjects:

• ребёнок боялся = the child was afraid
• девочка боялась = the girl was afraid

But with a plural subject like дети, gender is no longer shown on the verb:

• дети боялись = the children were afraid

So боялись is plural because дети is plural.