Learn Hardcore Finnish: Se on yleinen tapa Suomessa. - It is a common habit in Finland.

se = it / that (neutral 3rd person pronoun, very common)
tämä = this (physically or mentally “close”; often a bit more “pointing at it”)
hän = he / she (used for people in more formal/neutral style)

In everyday spoken Finnish, people often use se even for people (“it/he/she”), but in standard written Finnish you normally use:

hän for people
se for things, ideas, facts, situations

So here se is “it/that (thing we are talking about) is a common habit in Finland.”

Why is the verb on used, and what form is it?

on is the 3rd person singular present tense form of the verb olla (“to be”).

olla = to be (dictionary form)
minä olen = I am
sinä olet = you are (singular)
hän / se on = he / she / it is
me olemme = we are
te olette = you are (plural / formal)
he ovat = they are

So se on literally means “it is / that is”. Finnish doesn’t use an extra helper verb like English “do”; you just conjugate olla itself.

Why are yleinen and tapa in this basic form (no extra ending), and not something like yleistä tapaa?

Here, yleinen tapa is what’s called a predicative after the verb olla (“to be”). In Finnish, when you say X is Y in the sense of classifying or describing (not counting or measuring), both X (the subject) and Y (the predicative) are typically in the nominative (the “dictionary” form):

Se on yleinen tapa. = It is a common habit.
Hän on opettaja. = He/She is a teacher.
Tämä ruoka on hyvää. – here hyvää is partitive for a different reason (describing a mass/quality), but the basic rule is that nominative is normal for simple “X is Y” classification.

In this sentence:

yleinen = nominative singular adjective
tapa = nominative singular noun

They match because the adjective agrees with the noun in number and case. So if the sentence were in another case, both would change together, e.g.:

yleisestä tavasta = “from/about a common habit” (elative case)

The form yleistä tapaa (both in partitive) would belong in a different grammatical environment (e.g. as an object or in some more complex structure), not in this simple “X is Y” sentence.

Why does the adjective yleinen come before tapa? Could it come after?

In Finnish, adjectives almost always come before the noun they modify, just like in English:

yleinen tapa = common habit
pitkä mies = tall man
uusi auto = new car

Adjectives do not normally come after the noun as they often can in some other languages. So:

tapa yleinen is wrong in normal Finnish.

Also, adjectives typically agree with the noun in case and number:

yleinen tapa (nominative singular)
yleisen tavan (genitive singular)
yleisiä tapoja (partitive plural)

So in this sentence, yleinen is in the same form as tapa: nominative singular.

Why are there no articles like “a” or “the” in Se on yleinen tapa Suomessa?

Finnish has no articles at all—no words corresponding to English “a/an” or “the”. Whether you translate yleinen tapa as “a common habit” or “the common habit” depends entirely on the context, not on any special word in Finnish.

Se on yleinen tapa Suomessa.
→ “It is a common habit in Finland.” (most natural translation)

If you specifically needed “the common habit” you’d show that in other ways (context, word order, modifiers), but you still wouldn’t add an article in Finnish.

What does the ending -ssa in Suomessa mean?

The ending -ssa / -ssä is the inessive case, which basically means “in” or “inside” something.

Suomi = Finland
Suomessa = in Finland

Other examples:

kauppa = shop
kaupassa = in the shop
talossa = in the house (from talo, house)

You choose -ssa or -ssä depending on vowel harmony, but the meaning is the same: location “in”. So Suomessa literally means “in Finland.”

Can I change the word order, like Suomessa se on yleinen tapa or Se on Suomessa yleinen tapa?

Yes, Finnish word order is fairly flexible, and all of these are grammatically correct:

Se on yleinen tapa Suomessa.
– Neutral, very natural: “It is a common habit in Finland.”
Se on Suomessa yleinen tapa.
– Slight emphasis on “in Finland” as the place where this is true, almost “It is in Finland that it is a common habit.”
Suomessa se on yleinen tapa.
– Starts with the location, often used when contrasting with other places:
“In Finland it is a common habit (maybe unlike somewhere else).”

The basic information is the same; moving Suomessa around mainly changes the emphasis or topic–comment structure, not the core meaning.

Could I leave out Suomessa and just say Se on yleinen tapa?

Yes. Se on yleinen tapa is a perfectly good sentence and means “It is a common habit.” You would say this when:

The country or place is already clear from context, or
The location is not important; you just want to say that something is generally a common habit.

Adding Suomessa makes the sentence specifically about Finland:

Se on yleinen tapa. = It is a common habit (in general / in some context).
Se on yleinen tapa Suomessa. = It is a common habit in Finland (maybe not everywhere).

Could I drop se and say On yleinen tapa Suomessa?

You can say On yleinen tapa Suomessa, but it sounds more like a general, impersonal statement, roughly:

“(There) is a common custom in Finland”
or “It is (generally) a common custom in Finland.”

However, in most contexts where you are talking about a specific thing you’ve just mentioned, Finnish likes to keep the pronoun:

Se on yleinen tapa Suomessa.
= That specific thing we were talking about is a common habit in Finland.

Without se, it sounds less anchored to a specific antecedent and more like you’re just introducing the fact that such a habit exists.

Are there other ways to say “common habit” in Finnish besides yleinen tapa?

Yes, there are a couple of very close alternatives, with slightly different nuances:

yleinen tapa
– Very standard; “common, widespread habit/custom.” Neutral and good in almost any context.
tavallinen tapa
– Literally “ordinary/usual habit.” Emphasizes that it’s normal, nothing special, rather than the statistical idea of “widespread.” Often very close in meaning to yleinen tapa, though.
yleinen käytäntö
– “Common practice.” Used more for procedures, ways of doing things (e.g. in workplaces, institutions).

For the specific idea that something people do is a widely shared custom in the country, yleinen tapa is exactly the right and natural choice.

How would the sentence change if I wanted to say “They are common habits in Finland”?

You need to make everything plural:

Se on yleinen tapa Suomessa.
= It is a common habit in Finland.
Ne ovat yleisiä tapoja Suomessa.
= They are common habits in Finland.

Changes:

Se → Ne (singular “it/that” → plural “they/those”)
on → ovat (3rd person singular → 3rd person plural of olla)
yleinen tapa → yleisiä tapoja (adjective and noun in partitive plural)

Here yleisiä tapoja is in the partitive plural because you’re talking about some habits of that type, not identifying them as the complete set of all habits. This is the usual way to say “they are X-plural” in a non-exhaustive, descriptive sense.