Moja siostra nie lubi, kiedy w zupie jest za dużo czosnku, ale lubi smażone pieczarki.

Moja siostra is the subject of the sentence, so it stays in the nominative case.

• moja = my
• siostra = sister

If sister were the object, then you might see moją siostrę in the accusative. But here, she is the person doing the liking and not liking.

Nie lubi means does not like.

• lubi = he/she/it likes
• nie lubi = he/she/it does not like

The verb lubić is conjugated here for third person singular, because moja siostra is she.

So:

• ja lubię = I like
• ty lubisz = you like
• on/ona lubi = he/she likes

With nie, Polish usually writes it as a separate word with the verb: nie lubi.

In Polish, subordinate clauses are usually separated by commas. Here, kiedy w zupie jest za dużo czosnku is a dependent clause attached to nie lubi.

So the structure is roughly:

• Moja siostra nie lubi, kiedy...
• My sister doesn’t like it when...

That comma is normal and expected in Polish.

Yes, kiedy usually means when, and here it works like English when in a sentence such as:

• She doesn’t like it when there is too much garlic in soup.

So kiedy introduces the situation that she dislikes.

A more literal breakdown is:

• nie lubi, kiedy... = she doesn’t like it when...

After the preposition w meaning in, Polish often uses the locative case when talking about location.

• zupa = soup
• w zupie = in the soup

So zupie is the locative singular form of zupa.

This is a very common pattern:

• w domu = in the house
• w szkole = at school / in school
• w zupie = in the soup

After expressions like dużo (a lot of) and za dużo (too much / too many), Polish usually uses the genitive case.

• czosnek = garlic
• czosnku = genitive form of czosnek

So:

• dużo czosnku = a lot of garlic
• za dużo czosnku = too much garlic

This is an important pattern in Polish:

• dużo wody = a lot of water
• mało czasu = little time
• za dużo soli = too much salt

Jest means is. In this clause, Polish expresses the idea:

• when there is too much garlic in the soup

Literally:

• kiedy w zupie jest za dużo czosnku
• when in the soup is too much garlic

So jest is needed because Polish is saying that too much garlic is present in the soup.

Because pieczarki are the direct object of lubi, and for non-masculine-personal plural nouns, the accusative plural looks the same as the nominative plural.

• pieczarki = mushrooms
• smażone pieczarki = fried mushrooms

So here:

• lubi pieczarki = she likes mushrooms
• lubi smażone pieczarki = she likes fried mushrooms

The form smażonych pieczarek would be a different case, not the normal one used here.

Smażone is an adjective meaning fried, and it has to agree with pieczarki.

Since pieczarki is:

• plural
• non-masculine-personal

the adjective also takes the plural non-masculine-personal form:

• smażone pieczarki

This is adjective agreement, which is very important in Polish.

Compare:

• smażona pieczarka = a fried mushroom
• smażone pieczarki = fried mushrooms

Ale means but.

It connects two contrasting ideas:

• she does not like too much garlic in soup
• but she does like fried mushrooms

So the sentence has this structure:

• X, ale Y
• X, but Y

This is one of the most common conjunctions in Polish.

Not completely. Polish word order is more flexible than English, because case endings show grammatical roles. The sentence as given is natural and neutral:

• Moja siostra nie lubi, kiedy w zupie jest za dużo czosnku, ale lubi smażone pieczarki.

You could move some parts around for emphasis, but the original version sounds very normal.

For example, w zupie could sometimes move, but not every rearrangement sounds equally natural. For learners, the original order is a very good model to follow.

Not exactly. Pieczarki usually refers to the common cultivated mushrooms often sold in stores, especially button mushrooms.

So:

• grzyby = mushrooms in a broad sense
• pieczarki = champignons / button mushrooms

In everyday translation, mushrooms is often fine, but the Polish word is a bit more specific.

The main dictionary forms are:

• siostra = sister
• zupa = soup
• czosnek = garlic
• pieczarka = mushroom

In the sentence, some of them change form because of case:

• siostra stays siostra
• zupa becomes zupie
• czosnek becomes czosnku
• pieczarka appears in plural as pieczarki

This is a good example of how Polish nouns change depending on their role in the sentence.