Ako nam pošiljku pošalju tek sutra, nosit ćemo samo malu prtljagu.

This is a conditional sentence:

• Ako nam pošiljku pošalju tek sutra = If they send us the shipment only tomorrow / not until tomorrow
• nosit ćemo samo malu prtljagu = we will carry only a small amount of luggage

The first part gives the condition, and the second part gives the result. Croatian normally uses a comma when this kind of ako clause comes first.

Ako means if.

It introduces a condition:

• Ako... = If...

So the whole sentence means something like: If that happens, then we will do this.

This is very common in Croatian.

After words like ako and kad, Croatian often uses the present tense of a perfective verb to talk about a future action.

So:

• pošalju is grammatically present
• but in this sentence it means a future completed action: if they send

English usually uses present too after if:

• If they send it tomorrow, we will...

So in this respect, Croatian and English are actually quite similar.

Pošalju is the 3rd person plural present form of the perfective verb poslati.

It means:

• they send
• or in this sentence, more naturally, if they send

The ending tells you the subject is they, even though Croatian does not need to say oni.

Croatian often leaves subject pronouns out because the verb form already shows the person and number.

Here:

• pošalju = they send
• ćemo = we will

So Croatian does not need to say:

• oni pošalju
• mi ćemo nositi

Those pronouns can be added for emphasis, but they are usually omitted.

Nam means to us or for us.

It is the dative form of mi in its clitic version.

So:

• pošalju nam pošiljku = send us the shipment
• literally: send the shipment to us

It is an indirect object.

Because it is the direct object of pošalju.

The base form is:

• pošiljka = shipment, dispatch, package

Here it becomes pošiljku because it is:

• feminine
• singular
• accusative

So:

• pošiljka = nominative
• pošiljku = accusative

Tek adds the idea of only then, as late as, or not until.

So:

• sutra = tomorrow
• tek sutra = only tomorrow, not until tomorrow

This suggests delay. The speaker seems to mean that tomorrow is later than hoped or expected.

Both are possible in Croatian, but there is an important rule: the clitic ćemo normally cannot stand at the very beginning of its clause.

Because of that, Croatian often puts the infinitive first:

• nosit ćemo

When the future clitic comes after the infinitive, the infinitive usually loses its final -i:

• nositi → nosit ćemo

So these are both possible:

• nosit ćemo
• ćemo nositi (if something else comes before it)

In your sentence, nosit ćemo is the natural choice.

Because mala has to agree with prtljaga, and the whole phrase is the direct object of nositi.

Base forms:

• mala = small (feminine nominative singular)
• prtljaga = luggage (feminine nominative singular)

In the sentence, they become accusative singular:

• malu prtljagu

So both words change to match:

• mala prtljaga → malu prtljagu

Croatian prtljaga is also usually treated as a singular mass/collective noun, much like English luggage or baggage.

So:

• prtljaga does not usually mean one single suitcase
• it means luggage/baggage in general

That is why malu prtljagu means a small amount of luggage or light luggage, not necessarily one small bag.

Yes, Croatian word order is fairly flexible.

For example, the first clause could also be rearranged:

• Ako nam pošiljku tek sutra pošalju
• Ako nam tek sutra pošalju pošiljku

These versions are still grammatical, but the focus changes slightly. Croatian often moves words around to highlight what is important, such as tek sutra.

However, short unstressed words like nam and ćemo follow special placement rules, so not every order is equally natural.