Learn Hardcore Croatian: Poslije poluvremena izlazimo iz svlačionice i kapetanica nas podsjeća da se ne bojimo poraza. - After half-time we leave the locker room and the captain reminds us not to be afraid of defeat.

The base form (nominative) is poluvrijeme (neuter).
Genitive singular of neuter nouns ending in -e is typically -a → poluvrijeme → poluvremena.

The preposition poslije (after) normally requires the genitive case, so you say:

poslije poluvremena – after the halftime
(similarly: poslije utakmice, poslije škole, etc.)

Can I use nakon instead of poslije here? Is there any difference?

Yes, you can say:

Nakon poluvremena izlazimo iz svlačionice…

Poslije and nakon both mean after and both take the genitive.

Subtle differences:

nakon is often felt as a bit more formal or “bookish”.
poslije is very common in everyday speech and slightly more colloquial.

In this sentence, they are practically interchangeable.

Why is it iz svlačionice and not something like od svlačionice?

The preposition iz means out of / from the inside of and requires the genitive:

iz kuće – out of the house
iz škole – out of the school
iz svlačionice – out of the changing room

So svlačionice is genitive singular of svlačionica (feminine).

Od means from / away from in a more general sense, not specifically from inside something (od grada, od njega). Here, you are literally coming out of the locker room, so iz is the natural choice.

What tense is izlazimo here? Could it also refer to the future?

Izlazimo is present tense, 1st person plural (we) of izlaziti (to go out / to exit, imperfective).

However, in Croatian the present is often used:

for actual present:
Sada izlazimo iz svlačionice. – We are going out of the locker room (now).
for a planned or scheduled near future:
In sports narration or instructions, it can correspond to English we’ll go out, we come out.

In your sentence, it can be understood as a kind of narrative present describing what happens every time after halftime, or in a specific match being described live.

What is the difference between kapetan and kapetanica?

kapetan – captain (usually male or generic)
kapetanica – female captain (feminine form)

The suffix -ica is a common way to form feminine versions of some traditionally masculine roles:

učenik → učenica (male/female student)
glumac → glumica (actor/actress)
prvak → prvakinja (champion – irregular, but similar idea)

So kapetanica tells you that the captain is a woman.

Why is it nas podsjeća and not podsjeća nas? Can both word orders work?

Both kapetanica nas podsjeća and kapetanica podsjeća nas are grammatically correct, but there is a nuance.

Nas here is an unstressed pronoun (clitic), and clitics in Croatian prefer to stand early in the sentence, usually in “second position” (after the first stressed element):

Kapetanica nas podsjeća… – neutral, very natural.

You can say Kapetanica podsjeća nas…, but then nas is stressed for emphasis, as in:

Kapetanica podsjeća nas, a ne njih. – The captain reminds us, not them.

So, default/neutral: kapetanica nas podsjeća.
Shifted/stressed: kapetanica podsjeća nas (to emphasize us).

Why do we use nas and not mi?

Mi and nas are different cases of the same pronoun:

mi – nominative (subject): we
nas – accusative / genitive (object): us

In the sentence:

Kapetanica – subject (who? nominative)
podsjeća koga? – reminds whom? → nas (us, object)

So you must use the object form: nas, not the subject form mi.

What is the exact role of podsjeća here, and what is the difference between podsjećati and podsjetiti?

Podsjeća is:

3rd person singular, present tense of podsjećati (imperfective).

Verb pair:

podsjećati (imperfective) – to remind (ongoing, repeated, habitual)
podsjetiti (perfective) – to remind once, to give a reminder (completed action)

Examples:

Kapetanica nas podsjeća da… – The captain (regularly / now) reminds us that…
Kapetanica nas je podsjetila da… – The captain reminded us (once, completed) that…

In your sentence, the idea is that the captain is currently doing it, or does it habitually every time in that situation.

What does the da in da se ne bojimo poraza do? Is it like English “that”?

Yes. Da here introduces a subordinate clause that functions like English “that …”:

Kapetanica nas podsjeća da se ne bojimo poraza.
→ The captain reminds us *that we shouldn’t be afraid of defeat.*

This is often called a da-clause, used:

after verbs of saying, thinking, feeling, etc.:
kaže da, misli da, želi da, podsjeća da, etc.

So da simply links the main clause (kapetanica nas podsjeća) with what she reminds us of (da se ne bojimo poraza).

Why do we need se in da se ne bojimo? Could we just say da ne bojimo poraza?

You must use se here. The verb is inherently reflexive:

bojati se – to be afraid

It’s always used with se when you say who is afraid of what:

Bojim se poraza. – I’m afraid of defeat.
Ne bojimo se poraza. – We’re not afraid of defeat.

Without se, bojati changes meaning (to fight/struggle against something) and is normally not used like that in modern standard Croatian. So:

✓ da se ne bojimo poraza – correct
✗ da ne bojimo poraza – wrong in standard Croatian for the meaning “not to be afraid of defeat”.

Why is poraza in the genitive? Would nominative poraz be wrong?

Poraza is genitive singular of poraz (defeat).

The verb bojati se (to be afraid of) takes its object in the genitive case:

bojati se koga/čega? – to be afraid of whom/what?
- bojim se poraza – I’m afraid of defeat.
- bojim se mraka – I’m afraid of the dark.
- bojim se psa – I’m afraid of the dog.

Using nominative poraz here would be ungrammatical. The pattern is se bojati + genitive.

Why is the word order da se ne bojimo, and not da ne se bojimo or da ne bojimo se?

This is about clitic word order in Croatian.

Se is a clitic pronoun and wants to stand in a fixed position near the beginning of its clause. The standard order in a clause like this is:

da (subordinator)
first clitic(s), e.g. se
ne
main verb

So we get:

da se ne bojimo

Forms like da ne se bojimo or da ne bojimo se break the normal clitic-placement rules and sound wrong or very unnatural to native speakers. The natural sequence is exactly what you see in the sentence.

Could we express the idea differently, for example with strah instead of bojati se?

Yes, you can rephrase the idea using the noun strah (fear):

Kapetanica nas podsjeća da nemamo straha od poraza.
– The captain reminds us that we have no fear of defeat.

Or more naturally:

…da ne trebamo imati strah od poraza.
– …that we shouldn’t have fear of defeat.

However:

bojati se + genitive (bojimo se poraza) is the most direct and idiomatic way to say to be afraid of defeat.
Using strah changes the structure a bit and is slightly more abstract or formal.

The original sentence is very natural, especially in a sports context.