On jest bardzo cierpliwy, a jego siostra bywa niecierpliwa.

In Polish, "a" often shows a contrast between two people or things, but in a softer way than "ale" (“but”).

• "i" = and, just adding information, no contrast:

  • On jest bardzo cierpliwy i jego siostra jest cierpliwa.
    He is very patient and his sister is patient.

• "a" = and / while, often used for a contrast between subjects:

  • On jest bardzo cierpliwy, a jego siostra bywa niecierpliwa.
    He is very patient, while his sister tends to be impatient.

• "ale" = but, stronger, more direct opposition:

  • On jest bardzo cierpliwy, ale jego siostra jest niecierpliwa.
    He is very patient, but his sister is impatient.

So "a" here contrasts him with his sister in a natural, not-too-strong way.

Both are forms of the verb "być" (to be), but:

• "jest" = is, describing a stable or general fact:

  • On jest bardzo cierpliwy.
    He is very patient (as a general characteristic).

• "bywa" = is sometimes / tends to be / can be:

  • jego siostra bywa niecierpliwa
    his sister is sometimes impatient / tends to be impatient

"bywa" suggests that her impatience is not constant; it happens from time to time.
If you said „jego siostra jest niecierpliwa”, it would sound more like a stable personality trait.

Adjectives in Polish must agree with the gender of the noun:

• cierpliwy – masculine singular (for on – he)
• niecierpliwa – feminine singular (for siostra – sister)

So:

• On jest bardzo cierpliwy. – He is very patient.
  (on → masculine → cierpliwy)

• Jego siostra bywa niecierpliwa. – His sister tends to be impatient.
  (siostra → feminine → niecierpliwa)

Same pattern with other adjectives:

• On jest wysoki, a jego siostra jest wysoka.
  He is tall, and his sister is tall.

"jego" means "his". Polish needs a possessive word here to show whose sister it is.

• jego siostra = his sister
• siostra alone would just mean a sister / the sister, without specifying whose.

You could sometimes drop "jego" if the context is extremely clear, but the neutral, clear version is "jego siostra".

No. "bywa" is already the full verb here; you do not add "jest" after it.

Correct:

• jego siostra bywa niecierpliwa
  his sister tends to be impatient

Incorrect:

• ✗ jego siostra bywa jest niecierpliwa

Think of "bywa" as the equivalent of “is sometimes / tends to be” all in one word.

No, that sounds wrong in standard Polish.

The usual word order is:

• On jest bardzo cierpliwy.
  ([subject] [verb jest] [adverb bardzo] [adjective])

"bardzo" (very) almost always comes directly before the adjective or adverb it modifies:

• bardzo cierpliwy, bardzo wysoki, bardzo miły

So:

• ✅ On jest bardzo cierpliwy.
• ❌ On bardzo jest cierpliwy.

"bardzo" means "very" and it intensifies the adjective:

• cierpliwy – patient
• bardzo cierpliwy – very patient

Placement rules are simple:

• It goes immediately before the word it modifies:
  • bardzo cierpliwy, bardzo niecierpliwa, bardzo ładny

You cannot move it freely:

• ✅ On jest bardzo cierpliwy.
• ❌ On jest cierpliwy bardzo. (sounds unnatural as a neutral sentence; might appear in poetry or for strong emphasis)

In Polish, subject pronouns (on, ona, oni etc.) are often dropped because the verb form tells you the person.

So grammatically, you could say:

• Jest bardzo cierpliwy, a jego siostra bywa niecierpliwa.

However:

• Using "on" here makes it extra clear you are talking about he, especially at the start of a sentence or when changing topics.
• In many real conversations people would still say "On jest bardzo cierpliwy..." to introduce the person.

Both forms are correct; dropping "on" is just more typical in informal, flowing speech when the context is clear.

"jego siostra" is in the nominative case (mianownik), because it is the subject of the verb "bywa".

• Kto bywa niecierpliwy? – Who tends to be impatient?
  Jego siostra. – His sister.

The nominative is the base dictionary form:

• siostra (nominative singular) → used for the subject of the sentence.

You see case changes when the noun plays a different role, e.g.:

• Widzę jego siostrę. (accusative – I see his sister)
• Mówię o jego siostrze. (locative – I speak about his sister)

You would change both the pronoun and the adjective to feminine:

• Ona jest bardzo cierpliwa, a jej siostra bywa niecierpliwa.
  She is very patient, and her sister tends to be impatient.

Changes:

• on → ona (he → she)
• cierpliwy → cierpliwa (masculine → feminine)
• jego → jej (his → her)

Everything else stays the same structurally.

Approximate pronunciation (in simple English-like spelling):

• jego – yeh-go
• siostra – shyoh-strah (the "si" is like soft sh, and "o" is short, as in not)
• bywa – bih-vah (short y like the i in sit)
• niecierpliwa – nyeh-chyer-plee-vah
  
  • nie → nyeh
  • cier → chyer (like chair but with the tongue more forward)
  • pli → plee
  • wa → vah

Spoken smoothly:
"YEH-go SHYOH-strah BIH-vah NYEH-chyer-PLEE-vah."