Äitini kysyi, mitä mieltä olen siitä, että koneessa on niin vähän tilaa.

Äitini means my mother. The ending -ni is a possessive suffix meaning my.

So:

• äiti = mother
• äitini = my mother

Finnish can express possession either with just the suffix or with both a pronoun and a suffix:

• äitini = my mother
• minun äitini = my mother

Using just äitini is very natural and common, especially in written Finnish.

Kysyi is the past tense of kysyä (to ask).

• kysyä = to ask
• kysyy = asks / is asking
• kysyi = asked

So Äitini kysyi means My mother asked.

Mitä mieltä is part of a very common Finnish expression for asking someone’s opinion.

The full pattern is:

• olla jotain mieltä jostakin = to be of some opinion about something
• mitä mieltä olet...? = what do you think about ...?

Literally, mitä mieltä is something like of what mind/opinion. It does not translate word-for-word naturally into English, but it functions as:

• What do you think...?
• What is your opinion about...?

So in this sentence, mitä mieltä olen siitä means what I think about it / what my opinion is about it.

Because this expression requires the partitive form.

• basic form: mieli = mind / opinion
• partitive: mieltä

In the fixed phrase:

• olla jotain mieltä = to have some opinion / to think

you use mieltä, not mieli.

Examples:

• Olen samaa mieltä. = I agree.
• Olen eri mieltä. = I disagree.
• Mitä mieltä olet? = What do you think?

So this is something best learned as a set expression.

This is a very common question. In Finnish, reported speech does not always shift tenses the way English often does.

English often does this:

• She asked what I thought...

But Finnish may keep the tense that reflects the situation more directly:

• Äitini kysyi, mitä mieltä olen...

Here olen is present because it can mean what I think / what my opinion is at that time or still now. Finnish often keeps the subordinate clause in the tense that fits its own meaning, instead of automatically changing it because the main verb is past.

If the speaker wanted to emphasize a past opinion, olin could also be possible in some contexts, but olen is very natural here.

Siitä means about it / of it / about that, and it comes from se (it/that).

The expression olla jotain mieltä jostakin requires the thing being talked about to be in the elative case (-sta/-stä):

• jostakin = about something
• siitä = about it / about that

So:

• mitä mieltä olen siitä = what I think about it / what my opinion is about that

The siitä points forward to the following että clause.

In Finnish, it is very common to use both:

• siitä, että ...

This structure means roughly:

• about the fact that ...
• about how ...
• about that ...

So here:

• mitä mieltä olen siitä, että koneessa on niin vähän tilaa

means:

• what I think about the fact that there is so little space on the plane

The siitä belongs to the expression olla mieltä jostakin, and että introduces the content clause. Together they sound completely natural.

Että is a conjunction meaning that.

It introduces a subordinate clause:

• että koneessa on niin vähän tilaa = that there is so little space on the plane

So the sentence contains reported speech / an embedded thought:

• My mother asked [what I think] [about the fact that there is so little space on the plane].

Yes. Koneessa is the inessive form of kone, meaning in the plane / inside the plane.

• kone can mean machine or plane
• koneessa = in the machine / in the plane

In this sentence, the context strongly suggests plane, because there is so little space is a very natural thing to say about an airplane cabin.

Finnish often uses the inside case with vehicles when you mean being inside them:

• autossa = in the car
• junassa = on the train / in the train
• koneessa = on the plane / in the plane

English says on the plane, but Finnish uses a form that literally means in the plane.

Because vähän (little / not much) usually requires the following noun to be in the partitive.

• tila = space
• tilaa = space (partitive form)

So:

• vähän tilaa = little space / not much space

This is very similar to other Finnish quantity expressions:

• paljon aikaa = a lot of time
• vähän rahaa = little money
• niin vähän tilaa = so little space

Niin is an intensifier here, meaning so.

• vähän = little / not much
• niin vähän = so little

So:

• koneessa on niin vähän tilaa = there is so little space on the plane

This is not the same as niin ... kuin comparisons. Here niin simply strengthens vähän.

Here tila means space, which is treated like an uncountable idea, much like English space.

That is why tilaa in the partitive feels natural:

• on vähän tilaa = there is little space
• on paljon tilaa = there is a lot of space

If tila meant something more like a room or a space/slot in a countable sense, the grammar could be different, but here it clearly means general available room.

Because this is an embedded question, not a direct question.

In English:

• direct question: What do you think?
• embedded question: She asked what I think.

Finnish works similarly in the sense that the clause begins with the question phrase:

• mitä mieltä olen

But Finnish does not use English-style do-support, and its word order is generally less rigid.

So this clause is not built like a direct yes/no question. It is simply a subordinate clause headed by mitä mieltä.

Not in the same structure.

• minun mielestäni = in my opinion
• mitä mieltä olen = what I think / what my opinion is

The original sentence reports a question:

• Äitini kysyi, mitä mieltä olen... = My mother asked what I think...

If you used minun mielestäni, you would be making a statement instead:

• Minun mielestäni koneessa on liian vähän tilaa. = In my opinion, there is too little space on the plane.

So both are useful, but they do different jobs.

Yes, kone is a broad word. It can mean:

• machine
• engine
• airplane / plane in many contexts

Context tells you which meaning is intended. In this sentence, there is so little space strongly suggests airplane, not an ordinary machine.

If needed, Finnish can be more specific:

• lentokone = airplane

But in everyday speech, kone often means plane when the situation makes that obvious.

It breaks down like this:

• Äitini kysyi = My mother asked
• mitä mieltä olen siitä = what I think about it / what my opinion is about that
• että koneessa on niin vähän tilaa = that there is so little space on the plane

So the grammar is roughly:

• Main clause: Äitini kysyi
• Embedded question: mitä mieltä olen siitä
• Content clause linked to siitä: että koneessa on niin vähän tilaa

A very literal unpacking would be something like:

• My mother asked [of what opinion I am] [about that [that there is so little space on the plane]].

That sounds unnatural in English, but it helps show how the Finnish pieces fit together.