Моя старша сестра працює в лікарні, а молодший брат ще навчається в школі.

Because сестра is a feminine noun, and the possessive my has to agree with the noun’s gender in Ukrainian.

• мій = my, for masculine nouns
• моя = my, for feminine nouns
• моє = my, for neuter nouns
• мої = my, for plural nouns

So:

• моя сестра = my sister
• мій брат = my brother

In this sentence, сестра is feminine, so моя is the correct form.

The adjectives must agree with the nouns they describe in gender, number, and case.

Here:

• сестра is feminine singular, so старший becomes старша
• брат is masculine singular, so молодший stays молодший

So the endings are showing agreement:

• старша сестра
• молодший брат

This is very normal in Ukrainian. Adjectives change form depending on the noun.

Yes. In family contexts, Ukrainian often uses these adjectives the way English uses older and younger.

So:

• старша сестра = older sister / elder sister
• молодший брат = younger brother

Even though these forms look like ordinary adjectives, in family relationships they are commonly used this way.

Because Ukrainian often omits repeated possessives when the meaning is already clear.

The sentence begins with Моя старша сестра..., so it is already understood that the speaker is talking about their family members. Because of that, saying just молодший брат sounds natural.

You could say:

• Моя старша сестра працює в лікарні, а мій молодший брат ще навчається в школі.

That is grammatically correct too, but it is a bit more repetitive. The original sentence sounds smoother and more natural.

Because after в / у meaning in / at a location, Ukrainian usually uses the locative case.

The dictionary forms are:

• лікарня = hospital
• школа = school

But after в when talking about being somewhere, they change:

• в лікарні = in/at the hospital
• в школі = in/at school

So this is a case change, not a different word.

These are common feminine noun patterns.

• лікарня → у/в лікарні
• школа → у/в школі

Very roughly:

• many feminine nouns ending in -я change to -і
• many feminine nouns ending in -а also change to -і

Examples:

• кімната → у кімнаті
• Україна → в Україні
• станція → на станції

So лікарні and школі are exactly what you would expect in the locative.

Yes. в and у both often mean in / at. Ukrainian alternates between them mostly for ease of pronunciation and flow.

So these are both possible:

• працює в лікарні
• працює у лікарні

and

• навчається в школі
• навчається у школі

Writers and speakers choose the one that sounds smoother next to the surrounding words. In your sentence, в лікарні and в школі are completely natural.

А often links two ideas that are being contrasted or set side by side.

Here the sentence compares two family members:

• the older sister works in a hospital,
• whereas / while the younger brother is still studying at school.

So а works well because it gives a mild contrast or parallel comparison.

Compare:

• і = and
• а = and / while / whereas, with a contrastive feel

In this sentence, а is the more natural choice.

Here ще means still.

It tells you that the brother has not finished being a student yet. He is still studying.

Its position before the verb is very natural:

• брат ще навчається в школі

That is similar to English is still studying.

Depending on context, ще can also mean yet, more, or another, but here still is the right sense.

Навчається is from the verb навчатися, which means to study or to be in education. The ending -ся is a reflexive marker, but in many verbs it is just part of the normal dictionary form and doesn’t need to be translated literally.

So:

• навчатися = to study, to learn
• він навчається = he studies / he is studying

In this sentence, навчається в школі means that he attends school or is receiving education there.

English speakers often wonder whether -ся always means oneself. Not necessarily. Sometimes it has a reflexive meaning, but sometimes it is just how the verb is formed.

Yes, very often you could.

• вчиться в школі = studies at school
• навчається в школі = studies at school

Both are common, but навчається can sound a bit more formal or neutral in some contexts. Вчиться is very common in everyday speech.

So the original sentence is perfectly natural, but ще вчиться в школі would also be understandable and common.

Not necessarily. In Ukrainian, just like in English, the present tense can describe:

• what someone is doing right now
• what someone does generally / habitually

Here it most naturally describes a general situation:

• the sister works at a hospital
• the brother is still in school

So these present-tense forms are being used for current life facts, not only for actions happening at this exact second.

Ukrainian often omits subject pronouns when the subject is already clear.

The nouns themselves are given:

• сестра працює
• брат навчається

So there is no need to add:

• вона працює
• він навчається

Adding the pronouns would usually sound unnecessary unless you want emphasis or contrast.

A helpful stress guide is:

Моя́ ста́рша сестра́ працю́є в лікарні́, а молодший брат ще навча́ється в шко́лі.

A rough pronunciation guide for an English speaker:

• Моя ≈ mo-YA
• старша ≈ STAR-sha
• сестра ≈ ses-TRA
• працює ≈ prat-SYU-ye
• в лікарні ≈ v li-kar-NI
• а ≈ ah
• молодший ≈ MO-lod-shyi
• брат ≈ braht
• ще ≈ shche
• навчається ≈ nav-CHA-ye-tsya
• в школі ≈ v SHKO-li

The exact sounds are not identical to English, but this should get you close.

Ukrainian word order is fairly flexible, but the original order is the most neutral and natural.

Original:

• Моя старша сестра працює в лікарні, а молодший брат ще навчається в школі.

You can move things around for emphasis, for example:

• В лікарні працює моя старша сестра, а молодший брат ще навчається в школі.
• Молодший брат ще навчається в школі, а моя старша сестра працює в лікарні.

These are possible, but they change the focus. The original sentence is the best neutral version for a learner to model.

Because Ukrainian does not have articles.

So where English says:

• the hospital
• a hospital
• the school

Ukrainian simply says:

• лікарня
• школа
• в лікарні
• в школі

Context tells you whether the meaning is more like a, the, or just a general place name. That is why the Ukrainian sentence has no words corresponding to English articles.