Learn Hardcore Finnish: Olen iloinen tänään, koska ystäväni tulee kylään. - I am happy today because my friend is coming to visit.

So Olen iloinen already clearly means I am happy.
You can say Minä olen iloinen if you want to emphasize I (for example: I am happy, but others are not), but in a neutral sentence you normally just say Olen iloinen.

What is the difference between iloinen and onnellinen?

Both can be translated as happy, but they feel a bit different:

iloinen = cheerful, glad, in a good mood (often more temporary)
- Olen iloinen tänään. – I’m in a good mood today.
onnellinen = deeply happy, content, fortunate (often more long‑term or about life situation)
- Olen onnellinen perheestäni. – I’m happy about / with my family.

In this sentence, iloinen fits well because it’s about today and about a specific event (a friend coming to visit).

Can tänään go in a different place in the sentence?

Yes. Common options:

Olen iloinen tänään, koska ystäväni tulee kylään.
Tänään olen iloinen, koska ystäväni tulee kylään.
Olen tänään iloinen, koska ystäväni tulee kylään.

All are correct. The differences are about emphasis:

Starting with Tänään (Today) emphasizes today as the topic.
Putting tänään right after Olen or after iloinen is more neutral; the nuance is small.

Word order in Finnish is flexible, but the sentence you have is very natural.

Why is there a comma before koska?

Koska introduces a subordinate clause (a because‑clause):

Main clause: Olen iloinen tänään
Subordinate clause: koska ystäväni tulee kylään

In written Finnish, a comma is usually placed between a main clause and a subordinate clause, so we write:

Olen iloinen tänään, koska ystäväni tulee kylään.

In English we often skip the comma before because, but in Finnish it’s normally kept.

What exactly does ystäväni mean, and what is the -ni ending?

The base word is ystävä = friend.
The ending -ni is a possessive suffix meaning my.

ystävä = friend
ystäväni = my friend

So ystäväni literally means my friend, without needing a separate word for my.

Grammatically, in this sentence ystäväni is the subject of the verb tulee.

Is ystäväni singular or plural? Could it mean “my friends”?

It can be either singular or plural, depending on context:

Singular: ystäväni tulee = my friend comes
Plural: ystäväni tulevat = my friends come

Here, the verb is tulee (3rd person singular), so the meaning is my friend (one person).

If you wanted to be clearly plural, you would say:

Ystäväni tulevat kylään. – My friends are coming over.

Why is it tulee and not tulen or tulevat?

Finnish present tense verb endings:

tulen = I come
tulet = you (sg.) come
tulee = he / she / it comes
tulemme = we come
tulette = you (pl.) come
tulevat = they come

The subject here is ystäväni (my friend) = he/she (third person singular), so we use:

ystäväni tulee – my friend comes / is coming

Why is Finnish using present tense tulee for an event in the future?

Finnish does not have a separate future tense like English will.
The present tense is normally used to talk about the future when the time is clear from context or from a time expression:

Ystäväni tulee kylään. – My friend is coming over / will come over.
Huomenna sataa. – It will rain tomorrow.

Here, the context clearly tells us it’s about a near‑future visit, so tulee is understood as is coming / will come.

What does kylään mean exactly, and how is it formed?

Kylään comes from the noun kylä = village.
The form kylään is the illative case, which often means into / to a place.

However, mennä kylään or tulla kylään is an idiomatic expression meaning:

to go visit someone, to go over to someone’s place, to come for a visit

So ystäväni tulee kylään really means my friend is coming over (to my place) / coming for a visit, not my friend is coming to the village in a literal geographic sense (unless you specify that context).

Why does tänään also end with -än? Is it the same case as kylään?

They look similar, but function differently.

kylään is clearly illative case of kylä (village) = to the village / for a visit.
tänään is an adverb meaning today. It historically relates to case forms of tämä päivä (this day), but for a learner it’s best just to memorize tänään as a fixed adverb form.

So: both end in -än, but you should treat tänään simply as the normal word for today.

Could I say Olen tänään iloinen instead of Olen iloinen tänään? Does it change the meaning?

Yes, you can say:

Olen tänään iloinen, koska ystäväni tulee kylään.
Olen iloinen tänään, koska ystäväni tulee kylään.

Both are grammatically correct and mean the same thing in most contexts. The difference is only a slight shift in rhythm / emphasis:

Olen tänään iloinen: mild emphasis on today (today I am happy).
Olen iloinen tänään: more neutral; focus on being happy and then you add today.

In everyday speech, both are very natural.

Why is it ystäväni and not minun ystäväni?

Both are correct:

ystäväni – my friend
minun ystäväni – my friend

minun is the genitive form of minä (I), and ystäväni already has the -ni possessive suffix. You can:

Use only the suffix:
- Ystäväni tulee kylään.
Use both the pronoun and the suffix for stronger emphasis:
- Minun ystäväni tulee kylään. – My friend is coming (not someone else’s, or in contrast to another person’s friend).

In neutral sentences, just ystäväni is usually enough.

What does koska mean exactly? Is it the same as sillä?

Koska is a conjunction meaning because. It introduces a clause that gives a reason:

Olen iloinen tänään, koska ystäväni tulee kylään. – I am happy today, because my friend is coming over.

Sillä can also be translated as for / because, but:

koska is more common in everyday speech for because.
sillä is somewhat more formal or literary and often appears at the beginning of a new sentence or clause explaining or justifying something.

In this sentence, koska is the natural choice.

Could the order kylään tulee ystäväni work, and what would it mean?

Yes, Kylään tulee ystäväni is grammatically correct. The basic meaning is still My friend is coming over, but the emphasis is different:

Ystäväni tulee kylään: neutral focus on my friend as the subject.
Kylään tulee ystäväni: starts with to visit / over here; it can feel like:
- The one who is coming over is my friend (not someone else), or
- You’re emphasizing the arrival/visit more than who is arriving.

Word order in Finnish can shift what is emphasized, but the core meaning stays the same. In a simple, neutral statement, Ystäväni tulee kylään is the most typical.