Learn Hardcore Finnish: Minulla ei ole yhtään rahaa.

Minulla – “on me”; minä = I, and -lla is a case ending (adessive) that here marks the possessor.
ei – negative verb, “not / does not”.
ole – the verb olla (“to be”) in a special form used with negation.
yhtään – “any (at all)”.
rahaa – “money” in the partitive case (indefinite amount).

A more literal gloss is: “On me there is not any money.” → “I don’t have any money.”

Why is it Minulla and not Minä for “I” here?

Finnish doesn’t normally use a verb “to have” the way English does. Instead, it uses a structure that literally means “on/at me there is …”.

Minä = “I” (basic form, nominative case).
Minulla = “on me / at me” (adessive case, “on/at”).

Possession is expressed with Minulla on … (“I have …”) and, in the negative, Minulla ei ole … (“I don’t have …”). So Minulla is there because Finnish marks the possessor with this case ending, not as the grammatical subject.

So how do you generally say “I have …” in Finnish?

Use the same basic pattern:

Minulla on rahaa. – “I have (some) money.”
Sinulla on auto. – “You have a car.”
Hänellä on koira. – “He/She has a dog.”

Structure:
[Person in -lla/-llä] + on + [thing had]

For the negative:

Minulla ei ole rahaa. – “I don’t have money.”
Sinulla ei ole autoa. – “You don’t have a car.”

What exactly does yhtään mean, and when is it used?

Yhtään means roughly “any (at all)” / “even one”. Features:

Very common in negative sentences and questions.
Usually comes before a noun in the partitive singular:
- yhtään rahaa – any money (at all)
- yhtään ystävää – any friend (at all)

Examples:

Minulla ei ole yhtään rahaa. – I don’t have any money (at all).
Onko sinulla yhtään aikaa? – Do you have any time (at all)?

It makes the lack or smallness stronger than just leaving it out.

Why is it rahaa and not raha?

Raha is the basic form (nominative). Rahaa is the partitive form.

You use the partitive here because:

It’s an indefinite amount of a “mass” noun (“some money, any money”).
Finnish uses the partitive in negative sentences for the thing that is lacking.

So:

Minulla on rahaa. – I have (some) money.
Minulla ei ole rahaa. – I don’t have (any) money.

The same happens with many mass or “uncountable” nouns:

vettä (from vesi, water),
maitoa (from maito, milk), etc.

What’s the difference between Minulla ei ole rahaa and Minulla ei ole yhtään rahaa?

Both mean “I don’t have any money”, but:

Minulla ei ole rahaa. – neutral statement: I don’t have money / I don’t have any money.
Minulla ei ole yhtään rahaa. – stronger: “I don’t have any money at all”, “not a single cent”.

Yhtään adds emphasis, often implying complete absence.

Why isn’t it En ole yhtään rahaa or Minä en ole yhtään rahaa?

Because in Finnish, “I don’t have money” is not built with “I am not money”, but with the possession structure:

Correct: Minulla ei ole (yhtään) rahaa. – “On me there is not (any) money.”

Also, in this type of sentence:

The grammatical “subject” is rahaa (“money”), which is 3rd person.
The negative verb therefore appears as ei (3rd person), not en (1st person).

So:

Minulla ei ole rahaa. – literally: “On me, there is not money.”
En ole rahaa would literally be “I am not money”, which is nonsense here.

Is rahaa singular or plural? How would I talk about different “funds” or separate amounts?

Rahaa is singular partitive of raha and behaves like a mass noun: “money” in general.

To talk about separate sums/funds or “monies”:

rahoja – plural partitive of raha
- Minulla ei ole rahoja. – I don’t have (the) funds / I don’t have monies (more concrete, specific sums).
Rahani ovat pankissa. – “My funds are in the bank.” (here rahat is plural “funds / monies”)

Everyday “I don’t have any money” is almost always rahaa, not rahoja.

Can I leave out yhtään and just say Minulla ei ole rahaa?

Yes, completely natural:

Minulla ei ole rahaa. – I don’t have (any) money.
Minulla ei ole yhtään rahaa. – I don’t have any money at all.

The version with yhtään just adds emphasis. In many contexts, the shorter one is enough and very common.

Can I change the word order, like Yhtään rahaa ei ole minulla?

You can change the word order in Finnish, but it affects emphasis and naturalness.

Minulla ei ole yhtään rahaa. – neutral: “I don’t have any money.”
Yhtään rahaa ei ole minulla. – “Any money, there isn’t with me.” This sounds marked/poetic or like strong emphasis.

More natural variations are:

Minulla ei ole rahaa yhtään.
Rahaa ei ole minulla yhtään. (emphasizes that I, specifically, don’t have money)

For everyday speech, Minulla ei ole yhtään rahaa is the default.

How do I say related positive sentences like “I have some money” or “I don’t have much money”?

Using the same structure:

Minulla on rahaa. – I have (some) money.
Minulla on vähän rahaa. – I have a little (bit of) money.
Minulla on paljon rahaa. – I have a lot of money.

Negatives:

Minulla ei ole paljon rahaa. – I don’t have much money.
Minulla ei ole juuri rahaa. – I hardly have any money.
Minulla ei ole ollenkaan rahaa. – I don’t have any money at all. (similar to yhtään)

How do I ask “Do you have any money?” in Finnish?

Use the same possession structure, in question form:

Onko sinulla rahaa? – Do you have money? / Do you have any money?
Onko sinulla yhtään rahaa? – Do you have any money at all?

Notes:

Onko is the question form of on (“is/are”).
sinulla = “on you / at you” (2nd person singular, like minulla but for “you”).

What case is Minulla, and where else is the ending -lla/-llä used?

Minulla is in the adessive case (ending -lla/-llä).

Adessive often means “on, at, with”:

Location: pöydällä – on the table.
Having / possession: Minulla on kirja. – I have a book.
With tools/means: kynällä – with a pen.
Time expressions: kesällä – in (the) summer.

So in Minulla ei ole yhtään rahaa, the adessive marks who the money would be “on/at” – that’s how Finnish expresses possession.