Learn Hardcore Finnish: Hänen harrastuksensa on piirtäminen, ei pelaaminen.

In standard Finnish, a third‑person possessor is typically shown twice: with the genitive pronoun (hänen) and with the 3rd‑person possessive suffix -nsa/-nsä on the noun: hänen harrastuksensa “his/her hobby.” Using only the pronoun without the suffix (e.g., hänen harrastus) is colloquial and not standard in writing. You can, however, drop the pronoun if the owner is clear and keep only the suffix: Harrastuksensa on piirtäminen (context needed).

What exactly is going on inside the word harrastuksensa?

Base noun: harrastus “hobby.”
Many case/suffix forms use the “genitive stem,” which for -us words is harrastukse- (cf. genitive harrastuksen).
Add the 3rd‑person possessive suffix -nsa/-nsä to that stem → harrastuksensa “his/her hobby.”

Could I just say Hänen harrastus on piirtäminen?

That’s common in informal speech, but it’s not standard. In neutral/standard Finnish you should say Hänen harrastuksensa on piirtäminen. If you want to avoid the pronoun, use the suffix alone with a person you’ve already mentioned: Harrastuksensa on piirtäminen.

Why is it -nsa and not -nsä in harrastuksensa?

Vowel harmony. The suffix is -nsa after back vowels (a, o, u) and -nsä after front vowels (ä, ö, y). Harrastus has back vowels (a, u), so you get -nsa. With a front‑vowel word you’d have, e.g., hänen työnsä “his/her work” (from työ).

Why is the complement a -minen noun (piirtäminen, pelaaminen)?

Finnish often turns verbs into action nouns with -minen when you name an activity as a thing. With the copula olla (“to be”), you get structures like:

Hänen harrastuksensa on piirtäminen. “His/Her hobby is drawing.” If you use the verb harrastaa (“to be into, to do as a hobby”), the activity goes in the partitive:
Hän harrastaa piirtämistä, ei pelaamista.

Why is it on piirtäminen (nominative) and not on piirtämistä (partitive)?

With olla used for classification/identification (“X is Y”), the predicative is normally nominative: harrastus on piirtäminen. The partitive (piirtämistä) with olla is possible but adds a mass/quantity flavor (“it’s (some) drawing”), and is more typical in sentences like Se on/ei ole pelaamista (“That is/isn’t (the act of) playing”). In this sentence, you’re naming the hobby, so nominative piirtäminen is the neutral choice.

Why is there a comma before ei pelaaminen and where did ole go?

This is an ellipsis. The full form would be: Hänen harrastuksensa on piirtäminen, [se] ei ole pelaaminen. Finnish often omits repeated olla in a contrast like “A, not B,” and uses a comma to mark the contrast.

Could/should I use vaan or eikä here?

You can emphasize contrast with vaan (“but rather”) if you negate first:
- Hänen harrastuksensa ei ole pelaaminen, vaan piirtäminen.
Eikä (“nor”) is for linking two negatives: Ei X eikä Y. It doesn’t fit the given wording, which is “X, not Y.”

Does pelaaminen mean all kinds of “playing” (instruments, children’s play)?

No. Pelata/pelaaminen is for games and many ball sports (e.g., pelata jalkapalloa). For instruments use soittaa/soittaminen (e.g., soittaminen = playing an instrument). For children “playing,” use leikkiä/leikkiminen. So pelaaminen here means playing games/sports, not instruments or make‑believe play.

Why is the verb on singular? Could it ever be ovat?

Harrastuksensa is a single hobby here, so on (singular) is correct. If there were multiple hobbies as the subject, you’d use ovat:

Hänen harrastuksensa ovat piirtäminen ja maalaaminen.

Is there any article (“a/the”) hidden in Hänen harrastuksensa on piirtäminen?

Finnish has no articles. Definiteness is inferred from context. Hänen harrastuksensa already makes it specific (“his/her hobby”), and piirtäminen is an activity noun without an article.

Can I change the word order?

Yes. Common variants include:

Piirtäminen on hänen harrastuksensa, ei pelaaminen.
Hänen harrastuksensa ei ole pelaaminen, vaan piirtäminen.
Ei pelaaminen vaan piirtäminen on hänen harrastuksensa. All are grammatical; the choice affects emphasis.

How are piirtäminen and pelaaminen formed from the verbs?

They’re -minen action nouns built from the verb stems:

piirtää → stem piirtä-
- minen → piirtäminen (“drawing”)
pelata → stem pelaa-
- minen → pelaaminen (“playing [games/sports]”) Note the long vowels: ii in piirtä- and aa in pelaa- are pronounced long.

Any pronunciation tips for the sentence?

Double consonants and vowels are long: harrastuksensa (rr long), piirtäminen (ii long), pelaaminen (aa long).
Stress the first syllable of each word.
ä is a front vowel (like the “a” in “cat,” but longer/clearer).
In harrastuksensa, the cluster -kse- is pronounced as written: [kse].