Вона вкорочує рукав, тоді як кравець подовжує штани.

Because рукав is the direct object of вкорочує, and it is a masculine inanimate noun.

In Ukrainian, the accusative singular of masculine inanimate nouns is the same as the nominative singular. So:

• рукав = nominative singular
• рукав = accusative singular

That is why вкорочує рукав is correct for shortens the sleeve.

If it were a masculine animate noun, the accusative would usually match the genitive instead.

Штани means trousers / pants, and it is normally used only in the plural in Ukrainian.

This is similar to English words like pants, trousers, or scissors, which are also often treated as plural in form.

So:

• штани = trousers / pants
• there is no normal everyday singular form meaning one pant

That is why the sentence says подовжує штани = lengthens the trousers/pants.

Тоді як means while, whereas, or while at the same time.

In this sentence, it connects two actions and shows a contrast or comparison:

• Вона вкорочує рукав = She shortens the sleeve
• тоді як кравець подовжує штани = while / whereas the tailor lengthens the trousers

So it is not just about time; it often highlights that two different things are happening in contrast.

Because кравець is the subject of the second clause, so it stays in the nominative case.

In:

• кравець подовжує штани

the tailor is the person doing the action, so кравець is nominative.

You would see кравця in other roles, for example:

• Я бачу кравця = I see the tailor
• У кравця є майстерня = The tailor has a workshop / At the tailor’s place there is a workshop

They are in the present tense, third person singular:

• вона вкорочує = she shortens / she is shortening
• кравець подовжує = the tailor lengthens / is lengthening

Like in many languages, the Ukrainian present tense can be translated into English in more than one way, depending on context:

• She shortens the sleeve
• She is shortening the sleeve

Both can be possible.

They are imperfective forms.

That matters because the present tense in Ukrainian is normally used with imperfective verbs. These forms can describe:

• an ongoing action
• a repeated action
• a general process

So:

• вкорочує = is shortening / shortens
• подовжує = is lengthening / lengthens

If you wanted a completed action, you would usually use a perfective verb in the past or future, not the imperfective present.

Because вкорочувати and подовжувати are natural, compact verbs meaning to shorten and to lengthen.

They are the direct Ukrainian equivalents of those English verbs in many contexts, especially with clothes or physical objects.

So:

• вкорочувати рукав = to shorten a sleeve
• подовжувати штани = to lengthen trousers

You could sometimes say something like робити коротшим or робити довшим, but that often sounds more general or less idiomatic here. For tailoring, the single verbs are better.

Yes, often it can.

Ukrainian verbs usually show the person and number clearly enough that the subject pronoun is not always necessary. So:

• Вона вкорочує рукав
• Вкорочує рукав

Both can work, depending on context.

However, вона may be included for reasons such as:

• emphasis
• contrast
• clarity about who is doing the action

In this sentence, using Вона helps clearly set up the contrast with кравець.

Yes, Ukrainian word order is fairly flexible.

The sentence:

• Вона вкорочує рукав, тоді як кравець подовжує штани.

is neutral and natural.

But other word orders are also possible, depending on emphasis. For example:

• Рукав вона вкорочує, тоді як кравець подовжує штани.

This would put more focus on рукав.

Even though word order can move around, the case endings and verb forms help show who does what.

A rough pronunciation guide for an English speaker:

• вкорочує ≈ vko-RO-chu-ye
• подовжує ≈ po-dov-ZHU-ye

A few helpful points:

• є after a consonant often sounds like ye
• ж sounds like the s in measure
• stress is important:
  • вкоро́чує
  • подо́вжує

If you want to sound more natural, make sure the stressed syllable is clear.

Here it means a sleeve of a piece of clothing.

Ukrainian often does not need to spell out every detail if the meaning is clear from context. So рукав here naturally means a garment sleeve, not something more abstract.

Also, using the singular suggests one sleeve is being altered. If both sleeves were meant, you would normally expect the plural:

• вкорочує рукави = shortens the sleeves

Yes, but for two different reasons:

• рукав is singular because it refers to one sleeve
• штани is plural because the noun штани is normally plural by nature

So this is not a mismatch in grammar. It is just how those nouns work:

• one sleeve = рукав
• trousers/pants = штани

Sometimes yes, but the meaning would shift a little.

• а often means and/but, and can mark contrast:

  • Вона вкорочує рукав, а кравець подовжує штани.
  • This is natural, but a bit simpler and less explicit.

• поки usually means while in a more time-based sense:

  • Вона вкорочує рукав, поки кравець подовжує штани.
  • This is less natural here if you mainly want contrast.

• тоді як is especially good when you want while/whereas with a clear contrast between the two actions.

So in this sentence, тоді як is a strong and appropriate choice.