Когда суп был готов, мама взяла половник и разлила его по тарелкам.

Когда means when and introduces a time clause: Когда суп был готов = When the soup was ready.

Russian often uses когда exactly this way, just like English uses when to set the time for the main action. The structure here is:

• Когда суп был готов — subordinate time clause
• мама взяла половник и разлила его по тарелкам — main clause

So the whole sentence means: first the soup reached the state of being ready, then the mother did the next actions.

Был is the past-tense form of быть (to be).

In Russian, the verb to be is usually omitted in the present tense:

• Суп готов = The soup is ready

But in the past tense, Russian normally uses быть:

• Суп был готов = The soup was ready

So был is there because the sentence is talking about the past.

Here готов is the short form of the adjective готовый.

Russian often uses the short form of some adjectives when they are used as part of the predicate, especially for states or conditions:

• Суп готов = The soup is ready
• Дверь закрыта = The door is closed
• Я уверен = I am sure

The full form готовый is more like ready as a descriptive attribute before a noun:

• готовый суп = ready soup
• готовая еда = ready food

So after был, Russian prefers готов, not готовый.

Because суп is a masculine singular noun.

Short-form adjectives agree with the noun in gender and number:

• masculine: готов
• feminine: готова
• neuter: готово
• plural: готовы

So:

• суп был готов — soup is masculine
• каша была готова — porridge is feminine
• блюдо было готово — dish is neuter

In the past tense, Russian verbs agree with the subject in gender and number.

The subject here is мама, which is feminine singular, so the past-tense verbs are feminine singular too:

• взял — he took
• взяла — she took
• взяло — it took
• взяли — they took

And the same pattern applies to разлила.

So мама взяла and мама разлила mean mother took and mother poured/served out.

It is the direct object, so it is in the accusative case. But for inanimate masculine singular nouns, the accusative often looks exactly like the nominative.

So:

• nominative: половник
• accusative: половник

That is why you do not see a visible change.

Compare with a feminine noun, where the accusative would look different:

• мама взяла ложку — ложка becomes ложку

But with половник, nominative and accusative are the same in form.

Because суп is a masculine singular noun, and его is the accusative form used for it/him in this pattern.

Here it means it, not him:

• разлила его = poured it out / served it out

Russian pronouns follow grammatical gender, not natural gender. Since суп is grammatically masculine, the pronoun is masculine too.

This does not mean the soup is being treated like a male person. It is just grammar.

Russian often includes the object pronoun even when the meaning is clear from context.

So разлила его по тарелкам explicitly says that what she distributed into the bowls/plates was the soup.

Could Russian omit it? Sometimes, yes, depending on style and context. But including его sounds completely natural here and makes the sentence more explicit.

Разлить means something like to pour out into several containers or to distribute by pouring.

That fits this sentence perfectly: the mother ladles the soup and distributes it among several plates/bowls.

The prefix раз- often suggests spreading out or distributing. So:

• лить — to pour
• налить — to pour some amount into a container
• разлить — to pour out/distribute into multiple containers

That is why разлила is especially appropriate with по тарелкам.

Тарелкам is dative plural, used after по in a distributive sense.

Here по тарелкам means something like:

• into the plates
• among the plates
• into individual servings

This is a very common Russian pattern:

• раздать книги по студентам
• разложить вещи по местам
• разлить суп по тарелкам

So по + dative often shows distribution over multiple places, people, or containers.

Yes, in natural English we often say bowls for soup. But Russian тарелка can refer to a deep plate, including the kind used for soup.

So по тарелкам is perfectly normal Russian, even if the most natural English translation might be into bowls.

This is a good reminder that word-for-word matching between languages is not always exact.

Because Когда суп был готов is a subordinate clause placed before the main clause.

Russian normally separates subordinate clauses with a comma:

• Когда суп был готов, мама взяла половник...

This is very similar to English punctuation:

• When the soup was ready, Mom took a ladle...

So the comma is required here.

Yes. Russian word order is more flexible than English word order, because case endings show grammatical roles.

The version in your sentence is neutral and natural:

• Когда суп был готов, мама взяла половник и разлила его по тарелкам.

But other orders are possible for emphasis, for example:

• Когда суп был готов, половник взяла мама...
  This would sound marked and would emphasize mama as the one who took the ladle.

• Мама, когда суп был готов, взяла половник...
  Also possible, but less neutral.

So the given order is probably the most straightforward one for a learner to treat as the default.