U toj maloj vrećici nisu samo breskve nego i dvije paprike za salatu.

Because the preposition u means in here, and when u expresses location, it takes the locative case.

So:

• vrećica = bag, little bag
• u vrećici = in the bag
• toj maloj vrećici = in that small bag

All three words agree in gender, number, and case:

• toj = that (feminine singular locative)
• maloj = small (feminine singular locative)
• vrećici = bag (feminine singular locative)

So the whole phrase means in that small bag.

Yes. Vrećica is a diminutive form.

• vreća = sack, large bag
• vrećica = small bag, little bag

Croatian often uses diminutives very naturally, much more than English does. Sometimes they simply indicate size, and sometimes they can also sound more everyday or affectionate.

In Croatian, the negative form of to be is written as one word:

• nisam = I am not
• nisi = you are not
• nije = he/she/it is not
• nismo = we are not
• niste = you all are not
• nisu = they are not

So nisu samo breskve means they are not only peaches / there are not only peaches.

You cannot say ne su.

Because Croatian often leaves the subject unstated when it is clear from the verb form.

Here, nisu is 3rd person plural, and the implied subject is the plural group of things in the bag. In natural English, we would usually say something like:

• There aren’t only peaches in that small bag...
• In that small bag, there are not only peaches...

So Croatian uses plural agreement with the plural nouns being discussed, even though no separate pronoun is stated.

They are in the nominative plural here.

• breskva → breskve = peaches
• paprika → paprike = peppers

This happens because they function as the things being identified as present in the bag, in a structure with to be:

• nisu samo breskve nego i dvije paprike

Literally, this is something like:

• they are not only peaches but also two peppers

So nominative is natural here.

Nego i is part of the common pattern:

• ne samo ... nego i ...
• not only ... but also ...

In this sentence, the verb comes first, so the structure appears as:

• nisu samo breskve nego i dvije paprike

This still means:

• not only peaches but also two peppers

So:

• samo = only
• nego i = but also

Using just i would not express the same contrast as clearly.

Because the negation is already carried by the verb nisu.

Croatian can express this pattern in slightly different ways. Here the negative verb does the job:

• nisu samo breskve nego i dvije paprike

This is equivalent in meaning to the familiar not only ... but also ... pattern.

So you do not need a separate ne before samo because nisu already contains the negation.

Because paprika is a feminine noun, and the numeral two has different forms depending on gender.

• dva = two (masculine/neuter)
• dvije = two (feminine)

Since paprika is feminine, you say:

• dvije paprike = two peppers

Examples:

• dva stola = two tables
• dva sela = two villages
• dvije knjige = two books
• dvije paprike = two peppers

After the numbers 2, 3, and 4, nouns usually appear in a special form that, for many feminine nouns like paprika, looks the same as the genitive singular.

So:

• jedna paprika
• dvije paprike
• tri paprike
• četiri paprike
• pet paprika

For learners, the easiest practical rule is:

• after 2, 3, 4, feminine nouns like paprika usually appear as paprike
• after 5 and above, you usually get paprika

So dvije paprike is exactly what you should expect.

It means for salad or for making salad.

• za = for
• salatu = salad (accusative singular)

Croatian often does not use articles like a or the, so za salatu can be understood generally. In natural English, depending on context, you might translate it as:

• for salad
• for a salad
• for the salad

Here it most likely means the peppers are intended to be used in a salad.

Because the preposition za usually takes the accusative case.

So:

• salata = salad
• za salatu = for salad

Other examples:

• za djecu = for children
• za školu = for school
• za ručak = for lunch

Yes, Croatian word order is fairly flexible, and this sentence is arranged in a natural but not completely fixed way.

The given order:

• U toj maloj vrećici nisu samo breskve nego i dvije paprike za salatu.

puts the location first: In that small bag...

You could also hear variations like:

• Nisu samo breskve u toj maloj vrećici nego i dvije paprike za salatu.
• U toj maloj vrećici nisu samo breskve, nego i dvije paprike za salatu.

The meaning stays basically the same, but the focus can shift slightly depending on what the speaker wants to emphasize.

Yes, breskve is the plural of breskva, which means peach.

So:

• breskva = peach
• breskve = peaches

A nectarine is usually nektarina in Croatian.

In this sentence, paprike means peppers as vegetables, most likely bell peppers.

Croatian paprika can mean:

• a pepper as a vegetable
• paprika powder/spice, in some contexts

But here, because the sentence says dvije paprike (two peppers), it clearly refers to whole vegetables, not the spice.

And because they are za salatu, the most natural interpretation is two salad peppers / two bell peppers.

Very literally, it is:

• In that small bag are not only peaches but also two peppers for salad.

A smoother English version would be:

• There aren’t only peaches in that small bag, but also two peppers for salad.
• That small bag contains not only peaches but also two peppers for salad.

So the main building blocks are:

• U toj maloj vrećici = in that small bag
• nisu samo breskve = there are not only peaches / they are not only peaches
• nego i dvije paprike = but also two peppers
• za salatu = for salad