U torbi nedostaje jedna pelena, pa ću svratiti u trgovinu prije nego što dođem po djecu.

Because u can take two different cases depending on meaning:

• u + accusative = movement into something
  
  • Idem u torbu would mean something like I’m going into the bag (which usually makes no sense here).
• u + locative = being in something, location
  
  • u torbi = in the bag

So U torbi nedostaje jedna pelena means One diaper is missing in/from the bag.

Nedostajati / nedostati means to be missing, to be lacking, or sometimes to be absent.

In this sentence:

• U torbi nedostaje jedna pelena
  = There is one diaper missing from the bag

A useful thing to notice is that Croatian often phrases this differently from English. Instead of saying I’m missing one diaper, Croatian commonly says something more like One diaper is missing.

It can also be used in other contexts:

• Nedostaje mi novca. = I’m short of money / I lack money.
• Nedostaješ mi. = I miss you.

So the verb can mean either be missing/lacking or be missed, depending on context.

Because jedna pelena is the grammatical subject of nedostaje.

Croatian structures this idea as:

• One diaper is missing

So jedna pelena is in the nominative singular:

• jedna = feminine nominative singular of jedan
• pelena = nominative singular

Even though English might sometimes prefer We’re missing one diaper, Croatian here focuses on the missing item itself.

Jedna is not always strictly necessary, but it is natural if you want to stress one diaper.

Compare:

• Nedostaje pelena.
  = A diaper is missing / There’s a diaper missing.
• Nedostaje jedna pelena.
  = One diaper is missing.

So jedna makes the quantity explicit.

Here pa means something like:

• so
• therefore
• and so

It links the first idea to the consequence:

• U torbi nedostaje jedna pelena, pa ću svratiti u trgovinu...
• One diaper is missing from the bag, so I’ll stop by the store...

It is very common in everyday Croatian and often sounds more natural than a heavier connector.

Both are possible.

Croatian future I is built with:

• the auxiliary ću, ćeš, će...
• the infinitive, here svratiti

Two common word orders are:

• svratit ću
• ću svratiti

In this sentence, ću comes after pa, which is natural because Croatian clitics often appear in the second position of the clause:

• pa ću svratiti

So this is standard and natural Croatian word order.

Not exactly.

Svratiti means:

• to drop by
• to stop by
• to pop in
• sometimes to make a quick stop

So:

• svratiti u trgovinu = to stop by the store

It suggests a brief, practical visit, not just the general act of going somewhere.

Compare:

• Idem u trgovinu. = I’m going to the store.
• Svratit ću u trgovinu. = I’ll stop by the store.

So svratiti adds the idea of a short detour or quick errand.

Because this is motion toward a destination.

Again, with u:

• u + accusative = movement into/to
• u + locative = location in

So:

• svratiti u trgovinu = to stop by/go into the store
  (trgovinu = accusative singular)
• biti u trgovini = to be in the store
  (trgovini = locative singular)

This is one of the most important case patterns to learn in Croatian.

Prije nego što means before in the sense of before I do something.

It introduces a clause:

• prije nego što dođem po djecu
• before I come/go to pick up the children

It is longer than English before because Croatian often uses a full conjunction phrase here:

• prije = before
• nego što = than/that (part of the fixed expression)

You should learn prije nego što as a set phrase meaning before + clause.

Yes, it is a present-form verb, but that is normal here.

Dođem is the 1st person singular present of the perfective verb doći. After conjunctions like prije nego što, Croatian often uses a present-form verb to refer to a future event.

So:

• prije nego što dođem po djecu literally looks like before I come for the children but means
• before I pick up the children / before I come to get the children

This is very common in Croatian and other Slavic languages: a present form can refer to a future action when the context already makes the time clear.

Here po means to fetch, for, or to pick up when used with verbs of going/coming.

So:

• doći po djecu = to come for the children
• more natural English: to come pick up the children

This is a very common pattern:

• ići po kruh = to go get bread
• doći po auto = to come for the car
• skoknuti po mlijeko = to pop out for milk

So po here expresses the purpose of the movement: you are going/coming in order to get something or someone.

Because in this meaning, po takes the accusative.

The noun is:

• nominative singular: dijete = child
• nominative plural: djeca = children
• accusative plural: djecu

So:

• po djecu = for the children / to pick up the children

This form is a little tricky because djeca is an irregular collective plural noun.

In meaning, it is plural: children.

Grammatically, it behaves as a plural noun, even though its form is somewhat special. Its cases are irregular compared with more regular nouns.

Important forms:

• djeca = nominative plural
• djece = genitive plural
• djeci = dative/locative plural
• djecu = accusative plural

So in the sentence:

• po djecu = accusative plural

This is one of those nouns you usually just have to memorize.

Not in standard Croatian.

• djecu is standard Croatian
• decu is standard Serbian

So if you are learning Croatian, you should use:

• djeca
• djecu
• dijete

Yes, Croatian word order is fairly flexible, but the original order is natural.

The sentence is:

• U torbi nedostaje jedna pelena, pa ću svratiti u trgovinu prije nego što dođem po djecu.

Why it sounds natural:

• U torbi sets the scene first: in the bag
• nedostaje jedna pelena gives the key information
• pa introduces the consequence
• ću appears early because clitics tend to go in second position
• prije nego što dođem po djecu comes at the end as a time clause

You could rearrange parts for emphasis, but not all versions would sound equally natural. For learners, the original sentence is a good model.

Yes, literally doći means to come, but in this expression the whole phrase matters:

• doći po djecu = to come for the children
• in natural English: to come pick up the children

This often depends on the speaker’s point of view. Croatian uses doći where English may prefer go or simply pick up.

So don’t translate too literally word by word. The phrase as a whole means the speaker will collect the children.

Yes.

Trgovina can mean:

• store
• shop

In this sentence, either works:

• I’ll stop by the store
• I’ll stop by the shop

In many everyday contexts, trgovina often refers to a grocery store or general shop, depending on context.