Learn Hardcore Finnish: Tämä lukija opiskelee suomea kotona.

Tämä kirja = this book (I’m holding it or it’s right here)
Tuo kirja = that book (over there)
Se kirja oli hyvä = that book / it was good (we both know which book we’re talking about)

In Tämä lukija opiskelee suomea kotona, Tämä singles out a specific reader: this reader (here / in this context).

What exactly does lukija mean here? Is it like “reader” in English?

Yes, lukija literally means reader.

The verb lukea = to read
Add the suffix -ja/-jä to a verb → a person who does that action
- lukea → lukija = reader
- opiskella → opiskelija = student (literally “one who studies”)

So Tämä lukija = this reader. It could mean:

This person who is reading (e.g. the website, a blog, a book)
In some contexts, it’s a way to refer to “you, the reader”

It’s grammatically just a normal noun meaning a person who reads.

Why is there no word for “is” like in “This reader is studying Finnish at home”?

Finnish does not need a separate word for is when forming the present tense with most verbs.

English:

This reader is studying Finnish

Finnish:

Tämä lukija opiskelee suomea

The verb opiskelee already includes the information “(he/she) studies / is studying”:

opiskella = to study
opiskelee = (he/she) studies / is studying

So:

You do not say on opiskelee.
You only use on (is) with the verb olla itself or in certain structures (e.g. Hän on opiskelija = “He/she is a student”).

What form is opiskelee, and how is it built from opiskella?

Opiskelee is the 3rd person singular present tense of opiskella (“to study”).

Basic parts:

Infinitive: opiskella (to study)
Stem for present tense: opiskele-
3rd person singular ending: -e (no separate pronoun is required, the ending carries the person info)

Conjugation (present):

minä opiskelen = I study / I am studying
sinä opiskelet = you (sg) study
hän opiskelee = he/she studies
me opiskelemme = we study
te opiskelette = you (pl) study
he opiskelevat = they study

So Tämä lukija opiskelee… = This reader (he/she) studies / is studying…

Why isn’t there a pronoun like Minä or Hän in the sentence?

Finnish usually drops subject pronouns, because the verb ending already shows who is doing the action.

Opiskelen suomea. = I study Finnish.
Opiskelet suomea. = You study Finnish.
Opiskelee suomea. = He/she studies Finnish.

In your sentence, the subject is Tämä lukija, so a separate hän is not needed:

Tämä lukija opiskelee suomea kotona.
- Literally: “This reader studies Finnish at home.”

Adding hän here (Tämä lukija hän opiskelee…) would be ungrammatical in standard Finnish.

Why is it suomea and not suomi? What does that ending -a do?

Suomea is the partitive case of suomi (Finnish language).

suomi = Finnish (language), in the basic dictionary (nominative) form
suomea = Finnish, in the partitive form

In this kind of sentence, the object of verbs like opiskella (“to study”), puhua (“to speak”), ymmärtää (“to understand”) is usually in the partitive when it’s a language or an indefinite, ongoing activity:

Opiskelen suomea. = I study / am studying Finnish.
Puhun englantia. = I speak English.
Ymmärrän vähän ruotsia. = I understand a little Swedish.

So suomea here is:

Object of opiskelee
In partitive case, showing an ongoing/indefinite process of studying “some Finnish”, not a finished, countable amount.

Could you ever say opiskelee suomi instead of opiskelee suomea?

No, not in normal, correct Finnish.

With the verb opiskella, the language as an object is always in the partitive:

opiskella suomea (not suomi)
opiskella ranskaa (not ranska)
opiskella englantia (not englanti)

Using the nominative (suomi) here would sound clearly wrong to native speakers.

What does kotona mean exactly, and how is it different from koti or kotiin?

All three are forms of the same word koti (home), but with different cases that express different directions:

koti (basic form, nominative)
- Can be used as “a home” or in compounds, but not usually alone to mean “at home” or “to home”.
kotona = at home
- This is the inessive case (inside, “in / at”).
- Hän on kotona. = He/she is at home.
- Tämä lukija opiskelee suomea kotona. = This reader studies Finnish at home.
kotiin = (to) home
- This is the illative case (movement into).
- Menen kotiin. = I go home.
(For completeness) kotoa = from home
- This is the elative case (movement out of).
- Lähden kotoa. = I leave (from) home.

So in your sentence, kotona is correct because it describes where the studying happens: at home, not movement to or from home.

Can the word order be changed? For example, can I say Lukija opiskelee kotona suomea?

Yes, Finnish word order is relatively flexible, and your alternative is grammatically fine. Word order mainly affects emphasis and information structure, not basic grammar.

Some possible variants and typical nuances:

Tämä lukija opiskelee suomea kotona.
- Neutral: “This reader studies Finnish at home.”
Tämä lukija opiskelee kotona suomea.
- Slight extra emphasis on kotona (the place) before the object.
Kotona tämä lukija opiskelee suomea.
- Strong emphasis on at home (as opposed to somewhere else).

Basic subject–verb–object order is common, but rearranging is normal and often used for stylistic or emphasis reasons.

Is Tämä lukija behaving like an English “this + noun” phrase? Does Tämä agree with lukija in some way?

Yes. Tämä lukija works very similarly to this reader in English: Tämä modifies lukija.

In Finnish, demonstratives like tämä can agree in case and number with the noun:

Nominative singular: tämä lukija = this reader
Nominative plural: nämä lukijat = these readers
Partitive singular: tätä lukijaa = (of) this reader
Inessive: tässä lukijassa = in this reader (more abstract, but grammatically possible), etc.

In your sentence, both are in nominative singular because they form the subject:

Tämä lukija (subject) opiskelee (verb)…

How would I say “This reader studied Finnish at home” instead of “is studying”?

You switch opiskelee (present) to opiskeli (past). Everything else stays the same:

Tämä lukija opiskelee suomea kotona.
- This reader studies / is studying Finnish at home.
Tämä lukija opiskeli suomea kotona.
- This reader studied Finnish at home.

Finnish doesn’t have a separate “was studying” form like English; opiskeli can mean both studied and was studying, and context gives the nuance.

Is there any difference in meaning between “studies Finnish” and “is studying Finnish” in this Finnish sentence?

No grammatical difference: opiskelee covers both meanings.

English distinguishes:

studies Finnish (habitual)
is studying Finnish (ongoing right now / during this period)

Finnish:

Tämä lukija opiskelee suomea kotona.
- Can mean:
  - This reader generally studies Finnish at home.
  - This reader is currently (these days / right now) studying Finnish at home.

Context around the sentence usually clarifies whether it’s habitual or a current ongoing process.