Chcę być sobą.

Because sobą is the instrumental form of the reflexive pronoun siebie.

In Polish, the expression być sobą is a fixed and very common phrase meaning to be oneself or to be true to oneself. After być, Polish often uses the instrumental case for what someone is, especially in expressions of identity, role, or state.

So:

• siebie = genitive/accusative form
• sobie = dative/locative form
• sobą = instrumental form

Here, only sobą is correct.

Because it follows chcę, which means I want.

In Polish, after verbs like chcieć (to want), you usually use another verb in the infinitive:

• Chcę spać. = I want to sleep.
• Chcę iść. = I want to go.
• Chcę być sobą. = I want to be myself.

So być is in the infinitive because it works just like to be in English after want.

Chcę is the 1st person singular form of chcieć, meaning to want.

So:

• chcieć = to want
• chcę = I want

That is why the subject I is already built into the verb, and Polish does not need a separate word for I here.

Because Polish verbs usually already show the person.

Chcę already means I want, so ja (I) is not necessary.

You could say:

• Ja chcę być sobą.

but that adds emphasis, like:

• I want to be myself.

Without ja, the sentence sounds more neutral and natural.

Yes. Być sobą is a very common expression in Polish.

It means more than just a literal be yourself. Depending on context, it can suggest:

• being authentic
• not pretending
• acting naturally
• staying true to your identity

So it is worth learning as a whole chunk: być sobą.

Yes, but Chcę być sobą is the most neutral and natural order.

Polish word order is more flexible than English, so other orders are possible for emphasis, for example:

• Sobą chcę być.
• Być sobą chcę.

These are more marked or poetic. For everyday use, stick with:

• Chcę być sobą.

A rough guide is:

• chcę ≈ hts-en / hts-eh(n)
• być ≈ bitch but with a shorter vowel and a softer final consonant
• sobą ≈ SO-bon (with a nasal ending)

A few helpful notes:

• ch sounds like the ch in German Bach or Scottish loch
• ć is a soft sound, somewhat like a softened ch
• ą is a nasal vowel; at the end of a word it is often pronounced somewhat like on/om, depending on context

The natural stress is:

• CHCĘ być so-BĄ? Actually Polish normally stresses the second-to-last syllable of the whole word, not the sentence. So:
  • chcę = one syllable
  • być = one syllable
  • so-bą = stress on so

So the sentence sounds roughly like:

• chtsen bych SO-bon

Because the sentence means I want to be myself, where myself refers back to the same person as the subject.

Polish uses the reflexive pronoun siebie / sobie / sobą when the object or complement refers back to the subject.

Compare:

• Widzę siebie. = I see myself.
• Jestem sobą. = I am myself.
• Chcę być sobą. = I want to be myself.

You would not use a normal pronoun like mnie here.

Normally, no. That sounds unnatural.

Polish uses the reflexive pronoun in this kind of sentence, so the natural form is:

• Chcę być sobą.

Even though English says myself, Polish does not use the ordinary 1st person pronoun here.

Not always, but very often when talking about what someone or something is in terms of role, identity, profession, or character.

For example:

• Jest nauczycielem. = He is a teacher.
• Chcę być lekarzem. = I want to be a doctor.
• Bądź sobą. = Be yourself.

However, Polish also uses other patterns with być, especially in definitions, classification, or certain fixed structures. So it is better not to think być always = instrumental, but rather:

• być + instrumental is a very common and important pattern

And być sobą is one of the most standard examples.

The imperative is:

• Bądź sobą. = Be yourself.

This is a very common phrase in Polish, and it uses the same expression być sobą.

So you can connect the two:

• Chcę być sobą. = I want to be myself.
• Bądź sobą. = Be yourself.