Learn Hardcore Russian: Моя подруга немного волновалась перед таможней, но всё прошло быстро. - My female friend was a bit nervous before customs, but everything went quickly.

In some contexts, подруга can mean girlfriend (romantic), especially if it’s clear from the situation.
To be very clear about a romantic relationship, people often say девушка (my girlfriend) or моя девушка.

In your sentence, моя подруга is most naturally understood as my (female) friend, unless context elsewhere suggests a romantic meaning.

Why is it волновалась and not волновала or волновал?

Волновалась is:

past tense
feminine
reflexive
singular

The infinitive is волноваться – to worry / to be anxious (literally “to get worked up”).

Past tense forms of волноваться:

я / она волновалась
он волновался
оно волновалось
мы / вы / они волновались

Because the subject is моя подруга (female), the verb must be feminine: волновалась.

If you said волновала, that would mean she worried (someone else) with a non‑reflexive verb волновать (to disturb, to worry someone).

What does немного add here? Could I leave it out?

Немного means a little, a bit, somewhat.

Моя подруга волновалась перед таможней
→ My friend was worried before customs (sounds stronger, more general).
Моя подруга немного волновалась перед таможней
→ My friend was a bit worried before customs (milder, downplays the worry).

You can leave немного out; the sentence will still be grammatically correct. It will just sound like she was more plainly or clearly worried, instead of “just a bit”.

Why is it перед таможней and not перед таможню?

The preposition перед (before, in front of) always takes the instrumental case in modern standard Russian.

таможня (nominative, dictionary form)
таможней (instrumental, singular)

So:

✗ перед таможню – incorrect
✓ перед таможней – correct: before (going through) customs / at customs

This is a fixed grammar rule:
перед + instrumental (перед домом, перед школой, перед работой, перед таможней).

What exactly does таможня mean? Is it “customs office”, “customs control”, or just “customs”?

Таможня is a general word that can mean:

the customs service/authority as an institution
the customs checkpoint / control area at a border or airport
colloquially, the place where you go through customs checks

In your sentence, перед таможней is best understood as:

before the customs checkpoint
before going through customs

Not a specific word‑for‑word “office”, but the whole customs control situation/place.

Why is it всё прошло быстро and not все прошли быстро?

Всё прошло быстро literally: everything passed/went quickly.

Key points:

всё (with ё) here is a neuter singular pronoun meaning everything (as a whole situation).
прошло is neuter singular past: it passed / it went.

This is an impersonal-style construction where “everything” (the whole process, the whole situation at customs) is treated as one thing.

If you said все прошли быстро:

все (no ё) = everyone (all people)
прошли (plural) = went through / passed (somewhere)

That would mean: Everyone went through quickly (the checkpoint) – focusing on the people, not the situation as a whole. Both are grammatical, but the meaning and focus differ.

Why is всё spelled with ё? Is there any difference between все and всё?

Yes, there is both a spelling and meaning difference:

все (pronounced [fsʲe])
→ everyone, all (people/things) – plural
Example: Все пришли. – Everyone came.
всё (pronounced [fsʲo])
→ everything – neuter singular
Example: Всё прошло быстро. – Everything went quickly.

In everyday writing, Russians often omit the dots over ё, writing е instead, but here it is important for learners:

все прошло быстро (without dots) should be read as всё прошло быстро, not все.

Why is the verb прошло in neuter singular? What is its subject?

The subject is всё (everything), which is neuter singular in Russian. The past tense verb agrees with the subject in gender and number, so:

neuter singular subject (всё) → neuter singular past verb: прошло

Patterns:

он прошёл (masc.)
она прошла (fem.)
оно / всё прошло (neut.)
они прошли (pl.)

This kind of sentence (всё прошло …) is very common to talk about how an event went:

Всё прошло хорошо. – Everything went well.
Всё прошло спокойно. – Everything went calmly.

Why is it прошло (perfective) and not проходило (imperfective)?

Пройти / прошло (perfective) is used here because we’re describing the result / outcome of a completed event:

всё прошло быстро
→ the entire customs experience is over, and we’re summarizing how it went.

If you used проходило (imperfective):

Всё проходило быстро.
This would sound like you’re describing what was happening over some time in the past (more process-oriented), or comparing how something used to go.

For a single, finished event you’re summing up, Russians normally choose the perfective: прошло.

What is the nuance difference between волновалась and verbs like нервничала or переживала?

All of these can be translated as was worried / was nervous, but they have slightly different shades:

волновалась – was worried, agitated, emotionally tense
Neutral, very common. Can be about many things (exam, trip, meeting).
нервничала – was nervous (in a more tense, “nervy” way)
Suggests visible nervousness, irritation, fidgeting.
переживала – was worrying deeply / emotionally about something important
Often stronger, about outcomes that really matter (health, future, exam results).

In your sentence, немного волновалась sounds like mild, normal pre‑customs anxiety, not something dramatic. Немного нервничала would also fit and be very natural.