Learn Hardcore Croatian: Prije prošlog ljeta uopće nisam bila putovala u inozemstvo. - Before last summer I hadn’t travelled abroad at all.

The basic noun is ljeto (summer), neuter.
Genitive singular of ljeto is ljeta.
The adjective prošli (last) has to agree in case, gender and number with ljeto:
- Nominative: prošlo ljeto (last summer – as the subject or direct object)
- Genitive: prošlog ljeta (of last summer, before last summer, from last summer, etc.)

So:

Prije prošlog ljeta = Before last summer (with prije
- genitive)
On its own, prošlog ljeta is also genitive and is the normal way to say last summer in time expressions:
Prošlog ljeta sam putovala u inozemstvo. – Last summer I traveled abroad.

What tense is nisam bila putovala, and why are there two past elements?

Nisam bila putovala is the pluperfect (past perfect) in Croatian, called pluskvamperfekt.

Structure here:

nisam = ne
- jesam (1st person singular present of biti, used as auxiliary)
bila = past active participle of biti (to be), feminine singular
putovala = past active participle of putovati (to travel), feminine singular

So the pattern is:

present of biti + past participle of biti + past participle of main verb
(jesam) + bio/bila + putovao/putovala

Meaning-wise, it corresponds to English “I had (not) traveled”:

Prije prošlog ljeta uopće nisam bila putovala u inozemstvo.
= Before last summer I had not traveled abroad at all.

It emphasizes that this was your situation up to that past reference point (last summer).

Do people actually use this pluperfect in everyday speech, or would it be more natural to say nisam putovala?

In modern spoken Croatian, this full pluperfect (nisam bila putovala) is relatively rare and sounds formal, literary, or old‑fashioned in many contexts.

Everyday speech would much more often use just the normal past (perfect):

Prije prošlog ljeta uopće nisam putovala u inozemstvo.
Before last summer I didn’t travel abroad at all.

The time phrase prije prošlog ljeta already shows clearly that you’re talking about a time before another past event, so the simple past is usually enough in conversation.

You definitely need to recognize forms like nisam bila putovala (you’ll see them in books, formal speech, sometimes storytelling), but as a learner you can safely use:

nisam putovala instead of nisam bila putovala in almost all everyday situations.

Why is it bila and not bio – what does that tell me?

Bila is the feminine singular form of the past active participle of biti (to be). In Croatian, past participles agree with the subject in gender and number.

Forms of biti in the past participle:

masculine singular: bio
feminine singular: bila
neuter singular: bilo
masculine/mixed plural: bili
feminine plural: bile

So:

A woman would say:
Nisam bila putovala.
A man would say:
Nisam bio putovao.

In your sentence, bila tells us that the (implied) speaker is female.

What exactly does uopće mean here, and what nuance does it add?

Uopće means roughly “at all”. It strengthens the negation.

Compare:

Prije prošlog ljeta nisam bila putovala u inozemstvo.
Before last summer I hadn’t traveled abroad.
– neutral statement of fact.
Prije prošlog ljeta uopće nisam bila putovala u inozemstvo.
Before last summer I hadn’t traveled abroad *at all.
– emphasizes *total absence of such experience, almost like “not even once in any way”.

So uopće:

is usually used with negation (ne),
makes the denial stronger: “in no way, under no circumstances, at all”.

Where can uopće appear in this sentence, and does the position change the meaning?

The basic meaning stays the same – it still means “at all” – but word order can affect which part of the sentence feels emphasized.

Some natural options:

Prije prošlog ljeta uopće nisam bila putovala u inozemstvo.
– Fairly neutral; uopće is close to the negated verb.
Uopće nisam bila putovala u inozemstvo prije prošlog ljeta.
– Fronted uopće; sounds like strong emphasis: “I really hadn’t traveled abroad at all before last summer.”
Prije prošlog ljeta nisam uopće putovala u inozemstvo.
– Also possible; uopće focuses more narrowly on putovala.

You generally don’t separate uopće from the negation + verb too much. It tends to appear:

before the negated verb: uopće nisam putovala
or after the negation: nisam uopće putovala

The version you have is idiomatic; just remember uopće should stay near nisam (bila) putovala.

Why is it u inozemstvo and not u inozemstvu?

Because u + accusative expresses motion towards a place, while u + locative expresses location in a place.

Inozemstvo (foreign countries, abroad) is a neuter noun.

Accusative singular: inozemstvo
(to abroad / into foreign countries)
Locative singular: inozemstvu
(in/at abroad)

With putovati (to travel), you normally describe where you’re traveling to, so you use u + accusative:

putovati u inozemstvo – to travel abroad (to foreign countries)

Examples:

Putujem u inozemstvo. – I am traveling abroad. (destination → accusative)
Radim u inozemstvu. – I work abroad. (location → locative)
Živjela sam u inozemstvu. – I lived abroad. (location → locative)

What exactly is inozemstvo, and how is it used compared to words like vani?

Inozemstvo is a neuter noun meaning something like “foreign countries, abroad” as a general concept.

Typical patterns:

u inozemstvo – to abroad (destination, accusative)
u inozemstvu – abroad (location, locative)
iz inozemstva – from abroad (source, genitive)

Examples:

Idem u inozemstvo. – I’m going abroad.
Živi u inozemstvu. – He/She lives abroad.
Vratila sam se iz inozemstva. – I came back from abroad.

Vani is an adverb meaning “outside” or informally “abroad”:

Idem van(i). – I’m going out (or colloquially I’m going abroad).
On živi vani. – He lives abroad (colloquial).

So:

inozemstvo is more neutral/standard, especially in writing or formal speech.
vani is more colloquial and also means just outside (not necessarily another country).

Why is there no ja (I) in the sentence?

Croatian is a “pro‑drop” language: subject pronouns (like ja, I) are usually omitted because the verb form already shows the person and number.

In nisam bila putovala, the ending and the auxiliary clearly show:

1st person singular → I (had not) traveled

You would normally add ja only for emphasis or contrast:

Ja prije prošlog ljeta uopće nisam bila putovala u inozemstvo.
I, before last summer, hadn’t traveled abroad at all (unlike others).

But in a neutral sentence, leaving out ja is the most natural choice.

Why is the verb form putovala here, and what would the form be for a man?

Putovala is the past active participle of putovati (to travel), in:

feminine
singular

That matches the (implied) female subject.

Forms of putovati in the past participle:

masculine singular: putovao
feminine singular: putovala
neuter singular: putovalo
masculine/mixed plural: putovali
feminine plural: putovale

So:

A woman: Nisam (bila) putovala u inozemstvo.
A man: Nisam (bio) putovao u inozemstvo.

Also, putovati is imperfective aspect, which is the normal choice for talking about general experience or repeated/ongoing actions (like “have traveled, used to travel”), especially under negation.

Using a perfective verb (like otputovati) here would sound wrong: you’re talking about ever having that experience, so the imperfective is appropriate.

Could we use nikad instead of uopće? What’s the difference between nikad nisam putovala and uopće nisam putovala?

Yes, you can use nikad (never) in this context, but it’s not quite the same as uopće (at all).

Compare:

Prije prošlog ljeta nikad nisam putovala u inozemstvo.
– Before last summer I had never traveled abroad.
Emphasis: not even once before that point.
Prije prošlog ljeta uopće nisam putovala u inozemstvo.
– Before last summer I didn’t travel abroad at all.
Emphasis: complete absence of such activity in general.

In practice, these often overlap, and native speakers may even combine them for extra emphasis:

Prije prošlog ljeta nikad uopće nisam putovala u inozemstvo.
(very strong: I absolutely never at all used to travel abroad before last summer.)

For a learner, both nikad and uopće are useful with negation, but remember:

nikad – focuses on time / number of occurrences (never, not even once)
uopće – focuses on degree / totality (at all, in any way)