Кравець шиє рукав, тоді як я зашиваю дірку.

Because they are in the accusative case, and accusative forms depend on gender and animacy.

• рукав is a masculine inanimate noun, so in the singular its accusative form is the same as the nominative:

  • nominative: рукав
  • accusative: рукав

• дірка is a feminine noun ending in -а, so in the singular accusative it changes to -у:

  • nominative: дірка
  • accusative: дірку

So both are objects, but they decline differently.

They are related, but not identical.

• шити means to sew in a general sense.
• зашивати means to sew up, to stitch closed, or to mend by sewing.

So:

• кравець шиє рукав = the tailor is sewing a sleeve, probably as part of making or altering clothing
• я зашиваю дірку = I am sewing up a hole

In other words, шити is broader, while зашивати often suggests closing or repairing something.

Here, за- adds the idea of closing up or covering over by sewing.

Compare:

• шити = to sew
• зашивати = to sew up, stitch up
• зашити = to sew up completely / to finish sewing up

This prefix often changes the meaning from a general action to a more specific result. With дірка, that makes perfect sense: you are not just sewing randomly, you are sewing the hole closed.

Because the verbs agree with different subjects.

• кравець is third person singular: he/she tailors → шиє
• я is first person singular: I → зашиваю

So the forms match the subject:

• я зашиваю = I sew up
• кравець шиє = the tailor sews / is sewing

A quick comparison:

• я шию
• ти шиєш
• він / вона шиє

and

• я зашиваю
• ти зашиваєш
• він / вона зашиває

Тоді як is a conjunction meaning something like whereas, while, or while on the other hand.

In this sentence, it sets up a contrast between two actions:

• the tailor is sewing a sleeve
• I am sewing up a hole

It is a bit more explicit and formal than a simple а. Ukrainian often uses тоді як when contrasting two situations or actions happening side by side.

Because тоді як introduces another clause, and in Ukrainian clauses of this type are normally separated by a comma.

So the structure is:

• Кравець шиє рукав
• тоді як я зашиваю дірку

Each part has its own subject and verb, so the comma is expected.

Yes. Ukrainian word order is fairly flexible, because case endings already show what each word is doing.

The sentence as written is neutral and clear:

• Кравець шиє рукав, тоді як я зашиваю дірку.

But you could change it for emphasis:

• Я зашиваю дірку, тоді як кравець шиє рукав.
• Дірку я зашиваю, тоді як кравець шиє рукав.

These versions shift the focus, but the basic meaning stays the same. The original word order is probably the most straightforward for a learner.

Шиє is pronounced approximately shy-ye, more accurately [ˈʃɪjɛ].

It looks unusual because of є.

In Ukrainian, є often represents ye / je. After a vowel, it typically gives a y-sound before e. So:

• шиє = ши + є → shi-ye

That is why there is a glide sound in the middle.

Also, Ukrainian и is not the same as English ee. It is a different vowel, so try not to pronounce шиє like English shee-yeh.

Grammatically, кравець is a masculine noun, and it normally refers to a male tailor.

For a female tailor, Ukrainian commonly uses кравчиня.

So in this sentence, most learners would understand кравець as a male tailor. In some broader contexts, masculine profession nouns can be used more generally, but the basic form here is masculine.

Зашиваю is imperfective, which fits the idea of an action in progress or a general present-time action.

This matches the sentence well, because both actions are being presented side by side:

• the tailor is sewing
• I am sewing up

The perfective partner is зашити, but perfective verbs do not normally have a true present meaning in Ukrainian. Their present-looking forms usually refer to the future:

• я зашиваю = I am sewing up / I sew up
• я зашю or more standard future from perfective я зашию = I will sew up

So in this sentence, зашиваю is the natural choice.