Если автомат не принимает карту, можно заплатить наличными у кассира.

Because Если автомат не принимает карту is a subordinate clause introduced by если (if), and Russian normally separates that clause from the main clause with a comma.

So the sentence is structured like this:

• Если автомат не принимает карту = if the machine does not accept the card
• можно заплатить наличными у кассира = you can pay in cash at the cashier

This is very similar to English punctuation in sentences like If the machine doesn’t accept cards, you can pay cash at the cashier.

Если means if. It introduces a condition.

So:

• Если автомат не принимает карту = If the machine does not accept a card / your card

This sets up the situation under which the second part is true.

Here автомат means some kind of machine, usually a self-service payment machine, ticket machine, terminal, or vending-style machine depending on context.

In Russian, автомат is a broad word and often means an automated machine in public places.

Be careful: in other contexts, автомат can also mean automatic weapon, so context matters a lot.

Because карту is the accusative singular of карта.

The verb принимать here means to accept, and the thing being accepted is the direct object, so Russian uses the accusative case:

• nominative: карта
• accusative: карту

So:

• автомат принимает карту = the machine accepts the card

Принимает is from принимать, which can mean to accept, to take, to receive, depending on context.

In this sentence, it means:

• accepts a card as a method of payment

So автомат не принимает карту means the machine does not process or accept card payment.

Russian often uses the singular where English might use either singular or plural, depending on context.

Here карту can mean:

• a card
• the card
• your card

The exact nuance depends on the situation.

Using the singular is very natural because the sentence describes the act of inserting or using one card for payment.

Можно creates an impersonal construction meaning:

• it is possible
• one can
• you can

So можно заплатить literally means it is possible to pay, but in natural English it usually becomes you can pay.

This is very common in Russian when giving instructions, options, or general rules. It sounds less direct and more neutral than вы можете заплатить.

Compare:

• Можно заплатить наличными = It is possible / you can pay in cash
• Вы можете заплатить наличными = You can pay in cash

Both are correct, but можно is especially common in signs and practical instructions.

Заплатить is the perfective infinitive, while платить is imperfective.

After можно, Russian often chooses aspect based on meaning:

• заплатить = to pay, as a single complete action
• платить = to be paying / to pay in general / repeatedly

Here the sentence talks about one completed payment in a specific situation, so заплатить is the natural choice.

So:

• можно заплатить = you can pay
• less natural here: можно платить = you can be paying / you may pay regularly

Наличными is the instrumental plural form of наличные.

Russian often uses the instrumental case to express the means or method by which something is done.

So:

• заплатить наличными = to pay in cash

This is a very common pattern:

• платить картой = pay by card
• писать ручкой = write with a pen
• ехать поездом = go by train

Even though наличные literally means cash funds / cash money, the form наличными functions almost like an adverb here: in cash.

У кассира literally means at the cashier’s or with the cashier.

The preposition у is followed by the genitive case, so:

• кассир = cashier
• кассира = of the cashier / at the cashier’s / with the cashier

In this sentence, it means that instead of paying at the machine, you can pay to the cashier / at the cashier desk.

This is a very natural Russian way to express where or with whom a service happens.

Yes, в кассе is possible in some contexts, but it is not exactly the same.

• у кассира focuses on the person handling the payment
• в кассе focuses more on the cash desk / ticket office / checkout location

So:

• заплатить у кассира = pay at the cashier
• заплатить в кассе = pay at the cash desk / at the ticket office

In many real situations, both are understandable, but у кассира is especially natural when the cashier is viewed as the person you go to.

Yes. In Если автомат не принимает карту:

• автомат = subject
• не принимает = verb
• карту = direct object

So the first clause is a complete mini-sentence: the machine does not accept the card.

Because the second clause is built around the impersonal word можно.

Russian often leaves out a personal subject when the meaning is general:

• можно заплатить = one can pay / you can pay

There is no need to say вы unless the speaker wants to be more explicit or direct.

Yes, Russian word order is flexible, though some orders sound more natural than others.

The given version is very natural:

• Если автомат не принимает карту, можно заплатить наличными у кассира.

Possible variants include:

• Если автомат не принимает карту, у кассира можно заплатить наличными.
• Наличными можно заплатить у кассира, если автомат не принимает карту.

The basic meaning stays the same, but the emphasis changes:

• putting наличными earlier emphasizes the method
• putting у кассира earlier emphasizes the place/person

Usually it means in this situation / at this moment / for this machine.

Russian present tense can express a general fact or a current practical situation. Here the sentence is giving instructions, so the meaning is something like:

• If the machine does not accept your card / doesn’t take cards, you can pay in cash at the cashier.

It does not necessarily mean the machine is permanently unable to accept cards. Context decides that.

It is very natural. It sounds like something you might see or hear in a station, clinic, office, or store.

It uses several very common patterns:

• если for conditions
• можно for neutral instructions
• заплатить наличными for paying in cash
• у кассира for paying at the cashier

So it is a good example of practical everyday Russian.