Страхователь заполнил заявление о страховой выплате.

Заполнил is the perfective past tense. It presents the action as completed: the policyholder finished filling out the form.

Заполнял would be imperfective and would usually mean was filling out or filled out with the process emphasized rather than the completed result. In this sentence, the result matters, so заполнил is the natural choice.

That is the normal marker of the Russian past tense. In the past tense, Russian verbs also agree in gender and number:

• заполнил = masculine singular
• заполнила = feminine singular
• заполнило = neuter singular
• заполнили = plural

So here заполнил shows that the subject is being treated as masculine singular.

Заявление is in the accusative case because it is the direct object of заполнил.

It looks unchanged because заявление is a neuter inanimate noun, and for many nouns of this type, the accusative singular has the same form as the nominative singular:

• nominative: заявление
• accusative: заявление

So the case is different in function, even though the form stays the same.

The preposition о normally takes the prepositional case.

The base form is:

• страховая выплата = nominative

After о, both words change to prepositional singular:

• о страховой выплате

So:

• страховой = feminine singular prepositional of страховой
• выплате = feminine singular prepositional of выплата

This is a very common difference between Russian and English. Russian official style often uses заявление о ..., literally an application/statement about/regarding ..., where English often prefers application for ....

So заявление о страховой выплате is structurally application regarding an insurance payout, even though the most natural English translation may use for. The Russian preposition is chosen by Russian usage, not by word-for-word matching with English.

Not always. Страхователь is the person who takes out the insurance policy and is the party to the insurance contract. In English, this is often policyholder.

That is not necessarily the same as the person or thing being insured. Depending on the situation, the insured person, the beneficiary, and the policyholder can be different.

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

This sentence has a neutral, straightforward order:

• Страхователь заполнил заявление о страховой выплате.

But other orders are possible for emphasis, for example:

• Заявление о страховой выплате заполнил страхователь.

That version puts more focus on who filled it out. The basic meaning stays the same.

Russian has no articles, so it does not directly mark the difference between a/an and the.

You decide that from context. Depending on the situation, this sentence could mean:

• The policyholder filled out the application for the insurance payout
• A policyholder filled out an application for an insurance payout

If Russian needs to be more specific, it can use words like этот for this/the specific one or какой-то / один for some/a certain.

Grammatically, страхователь is a masculine noun. That is why masculine agreement is the default form here.

In real usage, such nouns can sometimes refer to a woman as well, especially in official language. If the speaker wants to show that the person is female, you may see feminine past-tense agreement in context, for example страхователь заполнила..., although official style often keeps things more neutral.

The stressed forms are:

страхова́тель запо́лнил заявле́ние о страхово́й вы́плате

A helpful breakdown:

• страхова́тель
• запо́лнил
• заявле́ние
• страхово́й
• вы́плате

Learning the stress is important in Russian because it is not always predictable from spelling.