Minä odotan rauhassa, kunnes passintarkastus on ohi ja voin mennä lähtöaulaan.

That is true: in Finnish, subject pronouns are often omitted because the verb ending already shows the person.

Here, odotan already means I wait / I am waiting, so minä is not strictly necessary. The sentence could very naturally be:

Odotan rauhassa, kunnes passintarkastus on ohi ja voin mennä lähtöaulaan.

Including minä can:

• add slight emphasis to I
• make the sentence a bit clearer
• sound more deliberate or contrastive in some contexts

So minä is optional here, not wrong.

Finnish often uses the present tense for both:

• what is happening now
• what will happen in the near future

So:

• odotan = I wait / I am waiting
• voin mennä = I can go / I’ll be able to go

In this sentence, the meaning is something like:

• I am waiting now
• until passport control is over
• and then I can go to the departure hall

This is very normal in Finnish. Finnish does not have a separate future tense like English.

Rauhassa comes from rauha, meaning peace or calm.

The ending -ssa is the inessive case, which often means in. So literally rauhassa is something like in peace / in calm.

In this sentence, odottaa rauhassa is an idiomatic expression meaning:

• wait calmly
• wait peacefully
• wait without rushing

So this is not just a literal location-like in peace. It is a common Finnish way to describe doing something calmly.

Kunnes means until.

That is exactly the meaning needed here: the waiting continues up to the point when passport control is finished.

• kunnes passintarkastus on ohi = until passport control is over

By contrast, kun usually means:

• when
• sometimes as or because, depending on context

So:

• kunnes marks an end point
• kun usually just introduces a time clause

That is why kunnes is the correct choice here.

Yes. Finnish very often forms compound nouns as one word.

Passintarkastus is made of:

• passi = passport
• tarkastus = inspection / check

Together, passintarkastus means passport control or passport check.

This is very typical Finnish word-building. English often uses separate words where Finnish uses one compound word.

Other similar examples:

• lentokenttä = airport
  
  • lento = flight
  • kenttä = field
• lähtöaula = departure hall
  • lähtö = departure
  • aula = hall / lobby

Ohi means over, past, or finished, depending on context.

In the structure olla ohi, it means:

• to be over
• to be finished

So:

• passintarkastus on ohi = passport control is over

This is a very common Finnish expression:

• Elokuva on ohi = The movie is over
• Kokous on ohi = The meeting is over

So on ohi is not strange or unusual here; it is a normal way to say that something has ended.

It does not need to, because the subject is still understood to be the same person as before: I.

The sentence has:

• main clause: Minä odotan rauhassa
• subordinate clause: kunnes passintarkastus on ohi
• coordinated continuation: ja voin mennä lähtöaulaan

In the last part, Finnish does not need to repeat minä, because voin already shows first person singular, and the subject is clearly the same speaker.

So:

• ja voin mennä... = and I can go...

If the subject changed, then Finnish would usually need to say it explicitly.

Because voin is the finite verb and mennä is the infinitive.

• voin comes from voida = can / be able to
• mennä means to go

After modal verbs like voida, Finnish normally uses the basic infinitive of the main verb.

So:

• voin mennä = I can go
• voin odottaa = I can wait
• haluan mennä = I want to go

This is similar to English:

• I can go
• I want to go

Lähtöaulaan is the illative case, which often means movement into something.

The base word is lähtöaula = departure hall.

The form lähtöaulaan means:

• into the departure hall
• to the departure hall, with the idea of entering it

This fits the verb mennä very well, because the sentence describes movement into a place.

Compare:

• lähtöaulassa = in the departure hall
• lähtöaulaan = into the departure hall

The ending looks like this because aula becomes aulaan in the illative singular, and the whole compound follows that pattern:

• aula → aulaan
• lähtöaula → lähtöaulaan

Because in Finnish, subordinate clauses are normally separated from the main clause with a comma.

Here:

• Minä odotan rauhassa = main clause
• kunnes passintarkastus on ohi... = subordinate clause

So the comma is standard Finnish punctuation.

This is one difference from English, where commas before words like until are often not used in the same way.

Yes. Ja means and, and here it connects:

• passintarkastus on ohi
• voin mennä lähtöaulaan

So the structure is roughly:

• I wait calmly,
• until passport control is over
• and I can go to the departure hall.

The subject of voin is still the same speaker, so Finnish does not repeat minä.

In other words, ja is linking two things that both belong to the time point introduced by kunnes:

1. passport control is over
2. I can go to the departure hall

Yes, this sentence is natural and correct.

A very common slightly less explicit version would be:

Odotan rauhassa, kunnes passintarkastus on ohi ja voin mennä lähtöaulaan.

This sounds natural because Finnish often omits minä unless there is a reason to emphasize it.

Depending on context, a speaker might also choose different wording, for example:

• Odotan rauhassa, kunnes passintarkastus on ohi. Sitten voin mennä lähtöaulaan.
• Odotan rauhassa, kunnes pääsen lähtöaulaan.

But the original sentence is perfectly good Finnish.