Решение по жалобе пришло вчера.

Because the subject is решение (decision), and решение is a neuter noun in Russian.

In the past tense, Russian verbs agree with the gender and number of the subject:

• masculine: пришёл
• feminine: пришла
• neuter: пришло
• plural: пришли

So:

• решение пришло = the decision came/arrived

Жалобе is in the dative singular.

The base form is жалоба (complaint). After the preposition по, Russian often uses the dative case in meanings like regarding, concerning, or in connection with.

So:

• жалоба = complaint
• по жалобе = regarding the complaint / on the complaint

This is a very common official or bureaucratic pattern in Russian.

Here по жалобе means something like:

• on the complaint
• regarding the complaint
• in response to the complaint

In official Russian, решение по жалобе is a set phrase meaning a decision on a complaint/appeal.

It does not literally mean movement along the complaint. The preposition по has many meanings, and this is one of its administrative/legal uses.

Yes. In Russian, приходить / прийти can be used not only for people, but also for things like:

• letters
• messages
• documents
• money
• information
• decisions

So решение пришло means that the decision was received, arrived, or came in.

It sounds natural in Russian, especially if the decision was sent from some office or authority.

Yes, it sounds fairly neutral-to-formal, and especially natural in an official, administrative, or legal context.

Решение по жалобе is the kind of phrase you often see in formal communication.

In everyday casual speech, a person might also say something like:

• Нам вчера пришло решение.
• Вчера пришёл ответ по жалобе.

But the original sentence is perfectly normal.

Russian has no articles like a/an or the.

So решение can mean:

• a decision
• the decision

The exact meaning depends on context.

In this sentence, English will usually use the because both speaker and listener probably know which complaint is being discussed:

• The decision on the complaint arrived yesterday.

The sentence is:

• Решение по жалобе пришло вчера.

This is a normal, natural order: subject + related phrase + verb + time

But Russian word order is flexible, so you could also say:

• Вчера пришло решение по жалобе.
• По жалобе решение пришло вчера.

These versions are all grammatical, but the emphasis changes a little.

For example:

• Вчера пришло решение по жалобе puts more focus on yesterday
• Решение по жалобе пришло вчера presents the decision first, then adds when it arrived

Пришло is the past tense of the perfective verb прийти.

Russian aspects here:

• приходить = imperfective, ongoing/repeated/general
• прийти = perfective, completed arrival

In this sentence, the arrival happened as a completed event yesterday, so perfective is the natural choice:

• Решение пришло вчера. = The decision arrived yesterday.

If you used the imperfective, it would usually suggest repetition, process, or a different context.

You might hear о жалобе in some contexts, but решение по жалобе is much more idiomatic in official Russian.

Why?

• о жалобе means about the complaint
• по жалобе means on/regarding the complaint, often with the sense that the complaint is the basis for the decision

In legal or administrative language, решение по жалобе is the standard phrase.

So for this meaning, по жалобе is the better choice.

No. Вчера is an adverb, meaning yesterday.

It does not change for case, gender, or number.

It simply tells you when the action happened:

• пришло вчера = arrived yesterday

You could say:

• Нам вчера пришло решение по жалобе.

That means:

• The decision on the complaint came to us yesterday
• or more naturally, We received the decision on the complaint yesterday

Adding нам makes the recipient explicit. Without нам, the sentence just states that the decision arrived, and the recipient is understood from context.

The stress is:

• решЕние
• по жалОбе
• пришлО
• вчерА

So the whole sentence is pronounced:

• решЕние по жалОбе пришлО вчерА

This is useful because past-tense neuter -ло forms often carry stress, as in пришлО.