Hän on minun ystäväni.

In standard Finnish, hän is the third-person singular pronoun for a person, and it does not show gender. So the same word is used for both he and she.

Finnish simply does not make that distinction in its personal pronouns the way English does. Usually the context tells you which person is meant.

On is the third-person singular present tense of olla, which means to be.

So:

• minä olen = I am
• sinä olet = you are
• hän on = he/she is

In this sentence, Hän on means he/she is.

Because minä means I, but minun means my.

More exactly, minun is the genitive form of minä. In Finnish, possession is often shown with a genitive pronoun:

• minä = I
• minun = my / of me

So minun ystäväni is a possessive phrase meaning my friend.

The ending -ni is a possessive suffix meaning my.

So:

• ystävä = friend
• ystäväni = my friend

Finnish often adds possession directly to the noun with a suffix. This is very different from English, where possession is usually shown only with a separate word like my.

Yes, they both mark possession.

In standard Finnish, it is possible to use:

• ystäväni = my friend
• minun ystäväni = my friend

Using both is grammatical and common in standard language. The version with both can sound a little more explicit, careful, or emphatic.

In everyday spoken Finnish, people often simplify this and say something like:

• mun ystävä = my friend

So for a learner, the important thing is:

• minun ystäväni = correct standard Finnish
• ystäväni = also correct
• mun ystävä = common spoken Finnish

It is basically ystävä in the nominative, plus the possessive suffix -ni.

Here ystäväni is a predicate noun after on. In a sentence like this, Finnish normally uses the nominative:

• Hän on opettaja. = He/She is a teacher.
• Hän on ystäväni. = He/She is my friend.

So the core noun is ystävä, and -ni is attached to it.

Because Finnish has no articles.

English needs words like a, an, and the, but Finnish does not. Whether something is best translated as a friend, the friend, or simply friend depends on context.

So ystäväni can be translated naturally as my friend without needing any article in Finnish.

Yes. It is correct and natural in standard Finnish.

However, in everyday speech, Finnish is often less formal. A speaker might say:

• Hän on mun ystävä.
• Se on mun ystävä.

A few notes:

• mun is the spoken form of minun
• in colloquial Finnish, se is often used for people too, even though standard Finnish prefers hän

So the sentence you have is a good standard model, even if casual speech often sounds different.

Yes, Finnish word order is more flexible than English word order, but the neutral order here is:

• Hän on minun ystäväni.

That is the most straightforward way to say He/She is my friend.

Other word orders are possible, but they usually add emphasis or sound more marked. For example, moving minun ystäväni to the front might emphasize my friend especially strongly.

So for a learner, this sentence is the safest basic pattern to use.

Yes, absolutely.

Hän on ystäväni is a correct sentence and also means He/She is my friend.

Compared with Hän on minun ystäväni, it can sound slightly less explicit because the separate pronoun minun is omitted, but the meaning is still clear because -ni already shows my.

So both are correct:

• Hän on ystäväni.
• Hän on minun ystäväni.

The longer version simply has double possession marking, which standard Finnish allows.