Ona je moje sestra.

She is my sister.

Breakdown of Ona je moje sestra.

• být: to be
• můj: my
• sestra: the sister
• ona: she

Questions & Answers about Ona je moje sestra.

Do I have to use Ona, or can I just say Je moje sestra?

In everyday Czech, the subject pronoun (já, ty, on, ona etc.) is usually dropped because the verb ending shows the person.

• Ona je moje sestra. – perfectly correct, but slightly emphatic: She is my sister (as opposed to someone else).
• Je moje sestra. – grammatically correct, but sounds a bit incomplete or unusually focused on the verb in isolation.
• The most natural way to say this is actually:
  To je moje sestra. – literally That is my sister, commonly used when identifying someone.

So:

• To state a fact / introduce someone: To je moje sestra.
• To stress that “she” (and not another woman) is your sister: Ona je moje sestra.

Why do Czechs often say To je moje sestra instead of Ona je moje sestra?

Czech very often uses to (literally that/it) in sentences of identity or classification:

• To je moje sestra. – That/This is my sister.
• To je učitel. – He is a teacher.
• To je auto. – It is a car.

This to + je + noun pattern is neutral and very common when:

• Pointing someone out.
• Introducing someone.
• Showing a photo, etc.

Ona je moje sestra is more like correcting or emphasizing:

• Ona je moje sestra, ne kamarádka. – She is my sister, not a friend.

So, To je moje sestra is what you’ll hear most often in real conversation.

Why is it moje sestra and not something like můj sestra?

Czech possessive adjectives (my, your, his…) change form according to the gender and case of the noun they describe.

For můj (my), the basic singular forms in the nominative are:

• můj – with masculine animate/inanimate nouns (e.g. můj bratr – my brother)
• moje (often shortened má in formal style) – with feminine nouns (e.g. moje sestra)
• moje – with neuter nouns (e.g. moje auto – my car)

Since sestra (sister) is feminine, you need the feminine form: moje.

So:

• můj bratr – my brother
• moje sestra – my sister
• moje dítě – my child

I’ve seen moje sestra and má sestra. What’s the difference?

Both have the same meaning: my sister.

• moje sestra – neutral, common in everyday speech and writing.
• má sestra – a shorter form; sounds more formal, literary, or stylistic.

In normal conversation, people almost always say moje sestra.
You’ll see má sestra more in written texts, books, or when someone wants to sound a bit more polished or poetic.

Why is it sestra and not sestru or something else after je?

In Czech, the verb být (to be) normally takes the nominative case on both sides of the verb when stating identity:

• Ona – nominative (subject)
• sestra – nominative (predicate noun)

So you get:

• Ona je moje sestra.

You would use sestru (accusative) after verbs that take a direct object, like:

• Vidím svou sestru. – I see my sister.
• Navštěvuju sestru. – I visit (my) sister.

With je (is) in a simple identity statement, you stay in the nominative: sestra.

Does the verb je change for gender? Why is it the same in Ona je and On je?

The verb je is the 3rd person singular of být (to be) in the present tense, and it does not change with gender:

• On je – he is
• Ona je – she is
• Ono je – it is

The form je only tells you person and number (3rd person, singular).
Gender is shown by the pronoun (on/ona/ono) or by context, not by the verb form.

For reference, present tense of být:

• já jsem – I am
• ty jsi – you are (singular informal)
• on/ona/ono je – he/she/it is
• my jsme – we are
• vy jste – you are (plural / formal)
• oni jsou – they are

Does moje always have to match the gender of the noun like this?

Yes. In Czech, possessive adjectives like můj / tvůj / náš / váš must agree with the noun in gender, number, and case.

In the basic nominative singular:

• můj bratr – my brother (masc.)
• moje sestra – my sister (fem.)
• moje auto – my car (neuter)

Later, in other cases, moje will also change form, for example:

• Vidím svou sestru. – I see my sister (accusative).
• O mojí sestře mluvím často. – I talk about my sister often (locative).

So, yes: the form of my is not fixed; it adapts to the noun.

Can I change the word order and say Moje sestra je ona?

You can say Moje sestra je ona, and it is grammatically correct, but it sounds very emphatic or contrastive, like:

• Moje sestra je ona, ne ta druhá dívka.
  My sister is that one, not the other girl.

Normal ways to state this idea:

• Ona je moje sestra. – She is my sister.
• To je moje sestra. – That/This is my sister. (most natural in context)

Changing word order in Czech is possible but often changes the focus or sounds unusual if the context does not demand it.

When would a native speaker actually say Ona je moje sestra?

This sentence is most natural when you want to emphasize or contrast the subject she:

• Correcting someone:
  Ona není moje kamarádka, ona je moje sestra.
  She is not my friend; she is my sister.
• Clarifying who you mean among several women:
  Víš, ta vysoká dívka? Ona je moje sestra.
  You know, that tall girl? She is my sister.

If you are simply introducing someone (no contrast), a native speaker will usually say:

• To je moje sestra.

How do I pronounce Ona je moje sestra?

Approximate pronunciation (in IPA and in rough English-like hints):

• Ona – [ˈɔna] – like “OH-nah”, with a short o as in off.
• je – [jɛ] – like “yeh” (the j is like English y).
• moje – [ˈmɔjɛ] – roughly “MO-yeh”, again short o.
• sestra – [ˈsɛstra] – like “SEH-strah”.

Word stress in Czech is always on the first syllable of each word:

• O-na je mo-je ses-tra (stress in bold: Ona je moje sestra).