Насчёт билета не волнуйся: я уже купил его.

Here насчёт means about, regarding, or as for.

In this sentence, Насчёт билета не волнуйся is something like:

• Don’t worry about the ticket
• As for the ticket, don’t worry
• Regarding the ticket, don’t worry

It is similar to о and про, but not always identical in tone:

• о билете = about the ticket
• про билет = about the ticket, more conversational
• насчёт билета = regarding the ticket / as for the ticket, often when talking about a practical matter

So насчёт is very natural here because the speaker is addressing a specific concern.

Because насчёт requires the genitive case.

The dictionary form is билет, but after насчёт it changes to билета:

• насчёт билета
• насчёт работы
• насчёт поездки

This is something you simply have to learn with the preposition: насчёт + genitive.

The standard form is насчёт, with ё.

However, in everyday Russian writing, native speakers often omit the dots and write насчет. That is very common. Even so, it is still pronounced насчёт.

For learners, it is useful to remember the version with ё, because it helps with pronunciation and stress.

Не волнуйся is the informal singular imperative of волноваться.

• волноваться = to worry / to get anxious
• волнуйся = worry
• не волнуйся = don’t worry

The -ся is there because the verb is reflexive: волноваться.

So this is not from волновать; it is from волноваться.

Also, in Russian, negative commands like don’t worry, don’t rush, don’t be afraid often use the imperfective verb, so не волнуйся is exactly what you would expect.

Yes. Не волнуйся is used when speaking to:

• one person
• informally

The formal or plural version is:

• Не волнуйтесь

So:

• не волнуйся = informal singular
• не волнуйтесь = formal singular or plural

Because купил is perfective, and here the speaker means the action is completed and the result matters.

• купить → купил = bought / has bought, completed action
• покупать → покупал = was buying / used to buy / bought in a process-oriented sense

In this sentence, the important idea is:

The ticket is already bought. The matter is taken care of.

That is why купил is the natural choice.

If you said я уже покупал его, it would sound wrong in this context, because it suggests something more like I have bought it before or focuses on the process rather than the completed result.

Его can mean different things depending on context:

• his
• him
• it

Here it means it, because it refers back to билет, which is a masculine noun.

So:

• билет = ticket
• я уже купил его = I already bought it

Russian does not have a separate word for it in the same way English does. Third-person pronouns depend on gender:

• masculine: его
• feminine: её
• plural: их

So его can refer to a masculine thing, not only a male person.

Yes, absolutely.

Both are natural:

• Я уже купил билет = I already bought the ticket
• Я уже купил его = I already bought it

Using его avoids repeating билет, since it was already mentioned in the first part of the sentence.

So the version in your example sounds smooth and natural because Russian, like English, often uses a pronoun when the noun is already clear.

The colon introduces an explanation or reason.

The structure is basically:

• Don’t worry about the ticket: I already bought it.

The second part explains why there is no need to worry.

Russian uses colons in much the same way English does in sentences like this.

Yes, the word order can change. Russian word order is flexible, but different orders give slightly different emphasis.

Your sentence:

• я уже купил его

is a neutral way to say I already bought it.

Other possible versions:

• Я его уже купил — also very natural; the pronoun is brought earlier
• Его я уже купил — stronger emphasis on it / that one
• Я купил его уже — possible, but less neutral here

So the original word order is good, but it is not the only possible one. In Russian, changing the order often changes the focus rather than the basic meaning.

Уже means already, and it often appears before the verb:

• я уже купил его

That is a very normal placement.

You may also hear:

• я его уже купил

Both are common. The exact position of уже is somewhat flexible, but it usually comes before the part of the sentence it is most closely connected with. Here it naturally highlights the fact that the buying has already happened.