Moje sestra se stěhuje do bytu nahoře, ale já budu bydlet dole vedle zahrady.

Because sestra is a feminine noun, and the possessive my has to agree with it.

• můj = my, used with masculine singular
• moje / má = my, used with feminine singular
• moje sestra = my sister

You may also see má sestra. Both moje sestra and má sestra are correct. Moje is often a bit more neutral or emphatic in speech, while má can sound slightly more compact or literary depending on context.

The verb is stěhovat se, which means to move house / relocate oneself.

So:

• stěhovat = to move something
• stěhovat se = to move oneself, to change where you live

Examples:

• Stěhuju nábytek. = I am moving furniture.
• Stěhuju se. = I am moving house.

So in Moje sestra se stěhuje..., the se is part of the verb itself.

Both are possible. Czech word order is flexible, and short unstressed words like se often come early in the sentence.

Here:

• Moje sestra se stěhuje do bytu nahoře.
• Moje sestra stěhuje se do bytu nahoře. → unnatural
• Moje sestra stěhuje do bytu nahoře. → wrong, because se is needed

The most natural options are usually:

• Moje sestra se stěhuje...
• Sestra se stěhuje...

In Czech, clitics like se usually take an early position, often after the first stressed element.

Because the preposition do takes the genitive case.

• basic form: byt = apartment / flat
• after do: do bytu = into / to the apartment

This is a very common Czech pattern:

• do domu = into the house
• do školy = to school
• do města = into the town/city

So do bytu is not a different word, just the genitive form of byt.

They describe two different ideas:

• stěhovat se = to move, to relocate
• bydlet = to live, to reside

So:

• Moje sestra se stěhuje do bytu nahoře = My sister is moving into the apartment upstairs.
• já budu bydlet dole = I will live downstairs.

One is about the change of residence, and the other is about the state of living somewhere.

Because bydlet is an imperfective verb, and in Czech the future of imperfective verbs is usually formed with:

být in the future + infinitive

So:

• budu bydlet = I will live
• budeš bydlet = you will live
• bude bydlet = he/she will live

This is the normal pattern.

By contrast, many perfective verbs form the future with a single present-looking form. But bydlet is imperfective, so it needs budu + infinitive.

Yes, it could be left out, because Czech often omits subject pronouns when the verb already shows the person.

So both are possible:

• ...ale já budu bydlet dole...
• ...ale budu bydlet dole...

Here já is included for contrast:

• my sister is moving upstairs,
• but I will live downstairs.

So já is not required for grammar, but it helps emphasize the contrast after ale.

They are adverbs of place:

• nahoře = upstairs / up above
• dole = downstairs / down below

In this sentence:

• do bytu nahoře = to the apartment upstairs
• budu bydlet dole = I will live downstairs

As adverbs, they do not change like nouns or adjectives do in this use.

They are very common in everyday Czech:

• Jsem nahoře. = I’m upstairs.
• On je dole. = He is downstairs.

Because vedle usually takes the genitive case when it means next to / beside.

• basic form: zahrada = garden
• after vedle: zahrady

So:

• vedle zahrady = next to the garden

This is similar to:

• vedle domu = next to the house
• vedle školy = next to the school

So again, the noun changes because the preposition requires a specific case.

Yes. In normal English translation, next to the garden and beside the garden are both fine.

Czech vedle covers this basic idea of something being adjacent to something else.

So dole vedle zahrady means something like:

• downstairs next to the garden
• downstairs beside the garden

The exact English wording depends on context, but the Czech structure is straightforward.

Sestra is in the nominative singular, because it is the subject of the sentence.

• Moje sestra se stěhuje...
• sister is the one performing the action

So the dictionary form sestra stays the same here.

If it had another role, the form might change. For example:

• Vidím sestru. = I see my sister.
  Here sestru is accusative.

Yes, but mostly in terms of focus and natural flow, not basic meaning.

The sentence is:

Moje sestra se stěhuje do bytu nahoře, ale já budu bydlet dole vedle zahrady.

This is natural because it presents information in a smooth order:

1. subject: Moje sestra
2. verb: se stěhuje
3. destination: do bytu
4. location detail: nahoře

Then the contrast:

1. ale já
2. future verb: budu bydlet
3. place: dole
4. more detail: vedle zahrady

Czech allows other word orders, but this version sounds neutral and natural.

A rough pronunciation guide:

• Moje ≈ MO-ye
• sestra ≈ SE-stra
• se stěhuje ≈ se STYE-hoo-ye
• do bytu ≈ do BI-too
• nahoře ≈ NA-ho-rzhe
• ale já ≈ A-le yaa
• budu bydlet ≈ BOO-doo BID-let
• dole ≈ DO-le
• vedle zahrady ≈ VED-le ZA-hra-dy

A few useful notes:

• ě often makes the preceding consonant softer; in stě-, English speakers often hear something like stye
• j in Czech sounds like English y
• ch in Czech is the throaty sound in German Bach or Scottish loch

So stěhuje can be approximated as STYE-hoo-ye, though the real Czech pronunciation is smoother than that.

In modern Czech, byt most commonly means apartment or flat.

In this sentence, do bytu clearly means into/to an apartment.

Do not confuse it with the verb být = to be:

• byt = apartment
• být = to be

They look similar, but they are different words with different pronunciation and meaning.