Возврат можно сделать в течение недели, а обмен — в течение месяца.

This is very common in Russian, especially in formal, retail, or customer-service language. Russian often uses nouns like возврат (return) and обмен (exchange) where English might prefer a verb phrase such as you can return it or you can exchange it.

So this sentence sounds natural for store rules, signs, and policies:

• возврат = a return
• обмен = an exchange

It is a bit more official and impersonal than using a direct verb.

Можно means it is possible / allowed / can.

Сделать literally means to do / to make, but in many contexts it works like carry out or perform. So возврат можно сделать means something like:

• a return can be made
• it is possible to make a return
• you can do a return

In natural English, we usually translate it more simply as you can return it.

Сделать is perfective, while делать is imperfective.

Here the speaker is talking about a single completed action: making a return or making an exchange. In store-policy language, that is the normal choice. The idea is not the ongoing process, but the fact that the action can be completed within a certain time limit.

So:

• сделать = to do/complete once
• делать = to do in general, repeatedly, or as a process

В течение means during or within the period of.

In this sentence, it gives the time limit:

• в течение недели = within a week / during the course of a week
• в течение месяца = within a month / during the course of a month

This expression is very common in formal Russian.

Because в течение requires the genitive case.

So:

• неделя → недели
• месяц → месяца

That is why you do not see неделю or месяц here.

A learner can think of в течение + genitive as a fixed pattern:

• в течение дня
• в течение недели
• в течение года

The dash shows that some words are omitted because they are understood from the first part.

The full version would be:

Возврат можно сделать в течение недели, а обмен можно сделать в течение месяца.

But Russian often avoids repeating the same words. So in the second part, можно сделать is left out, and the dash marks that omission:

а обмен — в течение месяца

This is very natural and common in written Russian.

А often connects two things that are being contrasted or compared, not necessarily opposed, but set side by side.

Here the sentence compares two different rules:

• return: one week
• exchange: one month

So а works well because it means something like:

• whereas
• while
• and as for

Using и would sound less natural here because the sentence is not just listing two facts; it is contrasting two time limits.

No, they are different.

• в течение недели = within a week / during the span of a week
• за неделю often means in a week in the sense of how long something takes to complete

Compare:

• Возврат можно сделать в течение недели = you are allowed to make the return within one week
• Я сделал это за неделю = I did it in a week

So в течение is about the allowed time window here, not the duration needed to perform the action.

Yes, that is grammatically possible:

Можно сделать возврат в течение недели, а обмен — в течение месяца.

That would also mean basically the same thing. The version with Возврат можно сделать... puts возврат first, which fits the style of rules or policy statements well. It highlights the type of action first: return versus exchange.

So the difference is mostly one of emphasis and style, not basic meaning.

In retail context, возврат usually refers to the act of returning a purchase. Depending on context, it can also imply the refund process. Russian often uses the same noun broadly in store language.

So in a sentence like this, a learner should understand возврат as a return of the purchased item, usually according to store policy.

If a speaker wanted to be more specific, they might use other words too, depending on the situation, but возврат is the standard general term here.

Yes, it sounds fairly formal or official, especially because of:

• the nouns возврат and обмен
• the expression в течение
• the impersonal structure можно сделать

This is exactly the kind of wording you might see:

• on a receipt
• on a store sign
• in return-policy terms
• on a website FAQ

In everyday spoken Russian, someone might say something more direct, such as a version meaning You can return it within a week, and exchange it within a month.