Проверь вложение, а я пока напишу письмо начальнице.

Проверь is the imperative form of the verb проверить — it means check! or have a look at.

So:

• проверить = to check
• проверь = check! (spoken to one person)

In this sentence, the speaker is telling someone to do something: Check the attachment.

Because it is the singular imperative, it usually suggests the speaker is talking to:

• one person,
• in an informal way, or
• in a neutral direct instruction.

If you were speaking politely or to more than one person, you would normally say проверьте.

Russian often omits subject pronouns when they are already clear from the verb form.

In English, you usually need you in commands only implicitly:

• Check the attachment.

Russian works the same way:

• Проверь вложение.

The verb form проверь already shows that the speaker is addressing you (singular), so adding ты would usually sound unnecessary unless you want emphasis.

Вложение literally means something like an enclosed item or attachment.

In modern everyday Russian, especially in email or messaging contexts, вложение commonly means:

• attachment
• a file attached to an email or message

So Проверь вложение most naturally means Check the attachment.

Depending on context, it could also refer more generally to an enclosed document or file.

Here вложение is the direct object of проверь, so it is in the accusative case.

But for many inanimate neuter nouns, the accusative looks exactly the same as the nominative.

So:

• nominative: вложение
• accusative: вложение

That is why the form does not change.

А can sometimes be translated as and, but it is not exactly the same as и.

In this sentence, а links two actions while also giving a sense of contrast, switch of focus, or meanwhile:

• You check the attachment, and I’ll write the letter/email to the boss in the meantime.

So а here is something like:

• and meanwhile
• while
• and as for me
• whereas

It often sounds more natural than и when two different people are doing different things.

No — here пока does not mean bye.

Russian пока has several meanings depending on context. In this sentence, it means something like:

• for now
• in the meantime
• meanwhile

So:

• а я пока напишу письмо начальнице = and I’ll write the letter/email to the boss in the meantime

Yes, пока can also mean bye in conversation, but not in this sentence.

Напишу is the future tense of the perfective verb написать.

Russian has two main aspects:

• писать = imperfective, focuses on process / repeated action
• написать = perfective, focuses on completing the action

So:

• я буду писать письмо = I will be writing a letter / I’ll be in the process of writing it
• я напишу письмо = I will write the letter / I’ll get it written

In this sentence, the speaker means a single completed action, so напишу is the natural choice.

Because in Russian, perfective verbs form the future with simple personal endings.

So:

• написать = to write (and finish)
• я напишу = I will write

By contrast, imperfective verbs usually need быть to form the future:

• писать = to be writing / to write in an ongoing sense
• я буду писать = I will be writing

So Russian distinguishes:

• simple future for perfective verbs
• compound future for imperfective verbs

Начальнице is the dative singular of начальница, which means female boss / female superior.

The verb написать письмо кому? uses the dative case for the recipient:

• написать письмо другу = write a letter to a friend
• написать письмо маме = write a letter to Mom
• написать письмо начальнице = write a letter to the boss

So начальнице means to the boss.

Yes. The noun начальница is feminine, so начальнице clearly refers to a female boss.

Compare:

• начальнику = to the male boss
• начальнице = to the female boss

So the sentence specifically tells us the boss is a woman.

It can mean either, depending on context.

In modern Russian, письмо may refer to:

• a traditional letter
• an email

Since the sentence also contains вложение (attachment), many learners would naturally assume this is a digital context, so письмо may well mean email here.

Russian often relies on context rather than using a separate everyday word for email in every situation.

Because а is a coordinating conjunction joining two clauses:

• Проверь вложение
• а я пока напишу письмо начальнице

In Russian, clauses joined by а are normally separated by a comma.

So the comma is standard punctuation here.

Yes. Russian word order is fairly flexible, and changing it usually affects emphasis rather than the core meaning.

For example:

• Проверь вложение, а я пока напишу письмо начальнице.
  Neutral, natural word order.

• Я пока напишу письмо начальнице, а ты проверь вложение.
  More emphasis on what I will do first in the sentence.

• Письмо начальнице я пока напишу...
  Stronger emphasis on the letter to the boss.

The original version sounds very natural and conversational.

It is most naturally informal or semi-informal because of проверь.

As noted earlier:

• проверь = singular informal command
• проверьте = polite singular or plural command

So if you were speaking to a colleague in a polite workplace register, you might say:

• Проверьте вложение, а я пока напишу письмо начальнице.

The rest of the sentence is neutral and works in many contexts.