Learn Hardcore Finnish: Jos tekee virheen, voi pyytää, että he leimaavat paperin uudestaan. - If you make a mistake, you can ask them to stamp the paper again.

This is the Finnish zero person construction: a verb in 3rd person singular with no stated subject. It means something like if one makes a mistake / if you make a mistake (in general) and one can ask / you can ask. It’s used for general instructions, rules, or typical situations where the agent isn’t a specific person.

A more direct “you” version would be:

Jos teet virheen, voit pyytää... = If you make a mistake, you can ask...

Why does it say Jos tekee virheen and not Jos teet virheen?

Jos tekee virheen is more impersonal/general (zero person). It reads like guidance: If someone/one makes a mistake…
Jos teet virheen addresses the listener directly: If you make a mistake…

Both are correct; the choice is mainly about style and how directly you want to address the reader/listener.

Why is virhe in the form virheen (not virhettä)?

Virheen is the total object form (often called accusative/genitive-looking in singular). It treats the mistake as a complete, countable event: to make a (specific) mistake.

Virhettä (partitive) would suggest an ongoing/indefinite amount: to make mistake(s) / to be making a mistake in a more “not bounded” sense.

Common contrasts:

tehdä virheen = make a (specific) mistake
tehdä virheitä = make mistakes (in general, plural)
tehdä virhettä can appear in some contexts, but virheen is the natural choice for “a mistake” as a single completed thing.

Is voi pyytää also “zero person”? Why not voit pyytää?

Yes. Voi pyytää continues the same zero person style: one can ask / you can ask (generally).
If you switch to direct address, it becomes:

voit pyytää = you can ask

So the sentence is internally consistent: both clauses keep the same impersonal tone.

What does pyytää, että... mean grammatically? Why use että here?

pyytää, että ... is a common way to express requesting that something happen: to ask that…

Here, että introduces a subordinate clause describing the requested action:

voi pyytää, että he leimaavat paperin uudestaan = you can ask that they stamp the paper again

Another common alternative is an infinitive structure:

voi pyytää heitä leimaamaan paperin uudestaan = you can ask them to stamp the paper again

Both are natural; the että-clause can feel slightly more “full sentence / explicit”.

Why is he used for “they”? I’ve heard Finns use ne for people.

In standard Finnish, he is the personal pronoun for people (they).
In spoken Finnish, many speakers often use ne for people too, even though it’s historically “they” for non-humans.

So:

Standard/written: he leimaavat
Spoken/common: ne leimaa (often also with colloquial verb form)

In this sentence, he fits a more formal/instructional tone.

Who does he refer to here? Is it okay that it’s vague?

Yes, it’s intentionally vague: he refers to the relevant officials/workers (e.g., office staff) in context. Finnish often allows this kind of generic reference when it’s obvious from the situation.

If you wanted to be more explicit, you could say:

voi pyytää virkailijaa leimaamaan paperin uudestaan = you can ask the clerk to stamp the paper again

Why is it he leimaavat paperin (active) instead of a passive like paperi leimataan?

Both are possible, but they emphasize different things.

Active with a subject:

että he leimaavat paperin uudestaan = focuses on the people who do it (they will stamp it)

Passive alternative:

että paperi leimataan uudestaan = focuses on the action/result (the paper will be stamped again), and avoids naming the doer

Passive is very common in Finnish for official processes.

Why is paperi in the form paperin?

paperin is the total object form: the action fully affects the object—they stamp the (whole) paper / the paper gets stamped (as a completed event).

If you used partitive paperia, it would suggest something incomplete or ongoing, which doesn’t fit well with stamping a document as a finished action.

What’s the difference between uudestaan and uudelleen?

They both mean again.

Typical nuance:

uudestaan = very common, often a bit more everyday
uudelleen = also common, can feel slightly more formal/neutral in some contexts

In many sentences, you can swap them with little change in meaning:

leimaavat paperin uudestaan / uudelleen

Could the word order change? For example, can I put uudestaan earlier?

Yes, Finnish word order is flexible, but changes can shift emphasis.

Neutral:

he leimaavat paperin uudestaan

Emphasize “again”:

he leimaavat uudestaan paperin (possible, but a bit marked)
että paperi leimataan uudestaan (very natural if using passive)

Most of the time, placing uudestaan at the end is the most straightforward.