U torbi imam keks s lješnjakom za put.

Because u meaning in takes the locative case when it shows location.

• torba = bag (basic/dictionary form, nominative)
• u torbi = in the bag (locative singular)

So:

• torba → nominative
• u torbi → locative after u

If u means movement into, it usually takes the accusative instead, but here the bag is just the location.

This is a case ending change. Torba is a feminine noun, and in the locative singular it becomes torbi.

A very common pattern for feminine nouns ending in -a is:

• nominative: torba
• genitive: torbe
• dative: torbi
• accusative: torbu
• locative: torbi
• instrumental: torbom

So u torbi is simply the correct case form after u for location.

Because Croatian often drops subject pronouns when they are already clear from the verb.

• imam = I have

The ending -am already tells you the subject is I, so ja is usually unnecessary.

You could say Ja imam..., but that adds emphasis, like I have... or As for me, I have....

Croatian often does not use a word like a/an because Croatian has no articles.

So imam keks can mean:

• I have a biscuit/cookie
• I have one biscuit/cookie (depending on context)

If you want to be more explicit, you can say:

• Imam jedan keks. = I have one biscuit/cookie.

But in normal speech, imam keks is perfectly natural.

Yes, it could be plural, but the sentence as written uses the singular.

• keks = a biscuit/cookie
• keksi or kekse = biscuits/cookies, depending on case

Here imam keks means the speaker has one biscuit/cookie, or is referring to it as a single item.

If you wanted plural, you might say:

• U torbi imam kekse s lješnjacima za put.

That would mean I have cookies/biscuits with hazelnuts in the bag for the trip.

Because the preposition s meaning with takes the instrumental case.

• lješnjak = hazelnut (nominative)
• s lješnjakom = with a hazelnut / with hazelnut (instrumental)

So the ending -om appears because of the case required by s.

This is a very common pattern:

• s prijateljem = with a friend
• s mlijekom = with milk
• s lješnjakom = with hazelnut

It describes the keks.

So keks s lješnjakom means something like:

• a biscuit/cookie with hazelnut
• a hazelnut biscuit/cookie

In natural English, you would often translate it more smoothly as a hazelnut cookie or a biscuit with hazelnut.

Croatian often uses s + instrumental where English might prefer an adjective or compound noun.

Both s and sa can mean with, but sa is mainly used to make pronunciation easier before certain consonant clusters.

Here s lješnjakom is natural and normal.

You may hear sa in examples like:

• sa mnom = with me
• sa sestrom = sometimes used because it flows better
• sa stola = from the table

So s is the basic form, and sa appears when needed for sound or ease of pronunciation.

Here za means for, expressing purpose: for the trip / for the journey.

After za, put is in the accusative case. For this noun, the accusative singular looks the same as the nominative:

• nominative: put
• accusative: put

So:

• za put = for the trip

This phrase is very natural in Croatian when talking about food, drink, or things prepared to take along.

Sometimes yes, but for the trip/journey is usually the safest translation.

In context, za put often means:

• to take along while traveling
• intended for the journey
• as travel food

So in English you might translate the whole sentence more naturally as:

• I have a hazelnut cookie in my bag for the trip.
• I have a hazelnut biscuit in my bag to take on the journey.

No, Croatian word order is fairly flexible, and changes in order often change emphasis, not basic meaning.

The sentence U torbi imam keks s lješnjakom za put. emphasizes the location a bit: In the bag, I have...

Other possible orders:

• Imam keks s lješnjakom u torbi za put.
• Keks s lješnjakom imam u torbi za put.
• Za put imam u torbi keks s lješnjakom.

These all sound slightly different in focus, but the core meaning stays similar.

Literally, it just means in the bag.

Croatian often leaves possession unspoken when it is obvious from context. So u torbi can naturally be understood as:

• in the bag
• in my bag

If you want to say it explicitly, you can say:

• u mojoj torbi = in my bag

But in everyday speech, that is often unnecessary.

Keks is a broad word and can correspond to English biscuit or cookie, depending on the variety of English and the exact food.

For a native English speaker:

• in British English, keks is often close to biscuit
• in American English, it may often be closer to cookie or cracker, depending on context

So you should choose the English word based on the actual food being described.

The lj in Croatian is a single sound, not a full l plus a full j pronounced separately in English style.

A rough guide:

• lj sounds somewhat like the lli in some pronunciations of million, though not exactly
• je sounds like ye or eh depending on the word
• š sounds like sh
• lj e š nj a k o m

So lješnjakom is roughly like lyesh-nya-kom, but that is only an approximation.

Also:

• š = sh
• nj is another single sound, similar to ny in canyon

Yes, it is grammatical and understandable, but in real life a native speaker might choose a slightly different wording depending on context.

For example:

• U torbi imam keks za put. = I have a cookie/biscuit in my bag for the trip.
• Imam u torbi keks s lješnjakom za put.
• Za put imam u torbi keks s lješnjakom.

The original sentence is fine; it just sounds a bit like a textbook sentence because it packs several grammar points together:

• u + locative
• omitted subject
• s + instrumental
• za + accusative