Я оплатил коммунальные услуги и сохранил квитанцию в папке.

Оплатил is the perfective past form, so it presents the payment as completed: the speaker finished paying.

• Я оплатил коммунальные услуги = I paid the utility bills / I have paid the utilities
• Я платил коммунальные услуги would sound odd in standard Russian, because платить is usually used either for an ongoing/repeated action or in different constructions.

A very common pair is:

• платить = to pay, be paying, pay regularly
• оплатить = to pay for something fully, to settle payment

So here оплатил fits because the sentence describes a completed action.

With оплатить, Russian usually takes the thing being paid for directly, without за.

• оплатить счёт
• оплатить проезд
• оплатить коммунальные услуги

This is different from the verb платить, which often does use за:

• платить за квартиру
• платить за электричество
• платить за коммунальные услуги

So both patterns exist, but they depend on the verb:

• оплатить + direct object
• платить за + accusative

That is why оплатил коммунальные услуги is correct.

It is in the accusative case, because it is the direct object of оплатил.

Dictionary form:

• коммунальные услуги

In this phrase, the accusative plural looks the same as the nominative plural because услуги is an inanimate plural noun.

So:

• nominative plural: коммунальные услуги
• accusative plural: коммунальные услуги

That is why the form does not visibly change here.

Коммунальные услуги means utility services or utilities, such as:

• electricity
• water
• gas
• heating
• trash collection
• other building/household services

In everyday English, this sentence would often be translated more naturally as I paid the utility bills rather than a very literal I paid коммунальные services.

Сохранил is the past masculine singular form of сохранить, a perfective verb meaning to save, to keep, or to store.

In this sentence, it means the speaker put the receipt away and kept it in a folder.

Depending on context, сохранить can mean:

• save a file
• preserve something
• keep something
• store something somewhere

Here it is about keeping the receipt in a folder, so saved/kept is the idea.

Because квитанцию is the accusative singular form, and it is the direct object of сохранил.

Dictionary form:

• квитанция = receipt

Accusative singular:

• квитанцию

So:

• Я сохранил квитанцию = I saved/kept the receipt

This is a very common pattern with feminine nouns ending in -а:

• папка → папку
• книга → книгу
• квитанция → квитанцию

В папке is in the prepositional case because it answers the question where?

• в папке = in the folder

Dictionary form:

• папка

Prepositional singular:

• в папке

With в, Russian often uses:

• accusative for motion into something
• prepositional for location in something

Compare:

• Я положил квитанцию в папку = I put the receipt into the folder
• Квитанция лежит в папке = The receipt is in the folder

In your sentence, в папке describes where the receipt was stored.

It can mean either, depending on context.

• physical folder for papers
• digital folder on a computer or phone

Because the sentence contains квитанцию, many learners first imagine a paper receipt in a physical folder, and that is probably the most natural reading. But in modern Russian, квитанция can also be an electronic receipt, so a digital folder is possible too.

Because the subject is я, and in the past tense Russian verbs agree in gender and number.

So if the speaker is male:

• я оплатил
• я сохранил

If the speaker is female:

• я оплатила
• я сохранила

If there were multiple people:

• мы оплатили
• мы сохранили

Russian past tense does not show person the way present tense does; it shows gender and number instead.

Yes, it can often be omitted.

Russian frequently drops subject pronouns when the subject is clear from context. So this sentence could also be:

• Оплатил коммунальные услуги и сохранил квитанцию в папке.

However, я may be included for:

• emphasis
• clarity
• contrast
• the start of a story or explanation

So both are possible, but я is not always necessary.

Yes, Russian word order is flexible, but the given version is the most neutral and natural.

This order simply presents:

1. the subject
2. the first completed action
3. the second completed action
4. the location of the receipt

You could change the order for emphasis, for example:

• Квитанцию я сохранил в папке. = It was the receipt that I kept in the folder.
• В папке я сохранил квитанцию. = It was in the folder that I kept the receipt.

But the original sentence is the best neutral version for ordinary statement style.

Usually, yes. The most natural reading is:

1. I paid the utilities
2. and then I saved/kept the receipt in the folder

Russian does not explicitly mark the sequence here with a word like then, but the order of the verbs strongly suggests it.

Because both verbs are perfective, the sentence sounds like a report of two completed actions in a practical sequence.

Both are possible, and the best choice depends on context.

• saved the receipt works well if you want a broad meaning, especially if it may be digital
• kept the receipt sounds very natural if you mean you did not throw it away
• filed the receipt in a folder is a very natural English translation if it is clearly a paper document

So in this sentence, possible natural translations include:

• I paid the utility bills and kept the receipt in a folder.
• I paid the utilities and saved the receipt in a folder.
• I paid the utility bills and filed the receipt in a folder.

All of these capture the Russian well.