Отлично, заявление о несогласии приняли.

Here Отлично is a reaction word meaning something like Great or Excellent.

It is not describing the verb приняли here. In other words, it does not mean they accepted it excellently. Instead, it is the speaker’s response to the news:

• Отлично, ... = Great, ...
• Отлично! can also stand on its own as Great!

So in this sentence it works like a separate comment on the situation.

Because Отлично is being used as a separate reaction before the main statement, much like English Great, ...

So the structure is:

• Отлично, = Great,
• заявление о несогласии приняли. = the main clause

The comma shows a pause between the speaker’s reaction and the actual information.

Literally, заявление о несогласии is something like:

• a statement about disagreement
• a declaration of disagreement
• depending on context, possibly an objection, a notice of disagreement, or a formal statement of non-agreement

The preposition о often means about or concerning.

So:

• заявление = statement, application, formal submission
• о несогласии = about disagreement / of disagreement

This is a very normal Russian noun phrase pattern:

• заявление о приёме на работу = an application for employment
• сообщение о проблеме = a message about a problem
• доклад о результатах = a report on the results

Because after о, Russian normally uses the prepositional case.

The dictionary form is:

• несогласие = disagreement

After о, it changes to:

• о несогласии = about disagreement

So:

• nominative: несогласие
• prepositional: о несогласии

This is why the ending changes from -е to -и.

Because заявление is not the subject here. It is the direct object.

The verb приняли is past tense plural and has an omitted subject meaning they. Russian often does this when the exact people are not important or are understood from context.

So the sentence means roughly:

• Great, they accepted the statement of disagreement.

This is a very common Russian pattern called an indefinite-personal construction:

• Меня пригласили. = They invited me. / I was invited.
• Документы подписали. = They signed the documents. / The documents were signed.
• Заявление приняли. = They accepted the application/statement. / The application was accepted.

There are two main clues.

1. The verb form

   • приняли = plural
   • If заявление were the subject, the verb would need to agree with it:
     • заявление приняло — grammatically possible in form, but not the intended meaning here and unnatural in this context

2. The case form

   • заявление is a neuter inanimate noun
   • In Russian, for many inanimate nouns, the accusative looks exactly like the nominative
   • So заявление can look the same whether it is a subject or a direct object

That means the verb is what really tells you what is happening here.

It is in the accusative singular, because it is the direct object of приняли.

However, for an inanimate neuter noun like заявление, the accusative singular looks exactly the same as the nominative singular:

• nominative: заявление
• accusative: заявление

So even though the form does not change, the function does: here it means they accepted what? — the statement.

Not necessarily.

In this kind of bureaucratic or official context, принять заявление usually means:

• to accept a document
• to receive it officially
• to take it for processing
• to register it

So заявление о несогласии приняли usually means the document was accepted/received by the relevant office or authority. It does not automatically mean they approved the content of the disagreement.

That nuance is important:

• accepted the filing is often closer than agreed with it

Russian word order is flexible.

Both are possible, but they can sound slightly different in emphasis.

• Приняли заявление о несогласии. = a more neutral They accepted the statement of disagreement.
• Заявление о несогласии приняли. = puts focus on the statement of disagreement itself, often as the key piece of news

In this sentence, after Отлично, the object-first order sounds very natural because the speaker is highlighting exactly what has now been accepted.

Yes. Even though Russian uses an active plural verb with an omitted they, English will often prefer a passive translation.

Possible translations include:

• Great, they accepted the statement of disagreement.
• Great, the statement of disagreement was accepted.
• Great, they accepted the objection.
• Great, the objection was received/accepted.

Which English version sounds best depends on the context, especially how formal or bureaucratic the situation is.