Learn Hardcore Finnish: Elokuvan loppu oli surullinen.

So elokuvan loppu literally means “the movie’s end” / “the end of the movie”.
Using elokuva loppu would be ungrammatical in this structure.

What is the ending -n in elokuvan doing, exactly?

The -n marks the genitive singular case in Finnish.

Pattern:

elokuva (movie) → elokuvan (of the movie)
talo (house) → talon (of the house)
tyttö (girl) → tytön (of the girl)

Whenever English uses “of X” or “X’s”, Finnish usually uses the genitive with -n (or some stem change + -n).
So elokuvan = of the movie / the movie’s.

What is the basic meaning and form of loppu here?

Loppu is a noun meaning end or ending.

loppu (nominative singular) = end, ending
In this sentence it's the subject: Elokuvan loppu = The end of the movie.

So structurally:

Elokuvan (genitive, modifier) + loppu (nominative, head noun)
→ Elokuvan loppu = the movie’s end / the end of the movie.

Why is the word order Elokuvan loppu, not Loppu elokuvan?

In Finnish, a genitive modifier normally comes before the noun it modifies.

elokuvan loppu = the movie’s end
ystävän auto = friend’s car
talon ovi = the house’s door / the door of the house

Loppu elokuvan would sound wrong or at least very odd in normal Finnish.
Poetic or highly marked word orders exist in the language, but for everyday speech and writing, put the genitive before the main noun.

Why is there no word for “the” in Elokuvan loppu oli surullinen?

Finnish has no articles (no “a/an” and no “the”).

Definiteness is normally understood from context, word order, and cases.
So elokuvan loppu can mean:

“the end of the movie” (most natural translation here), or
more generically “an end of a movie” in a different context.

English has to choose “a” vs “the”; Finnish simply doesn’t mark that grammatically.

What does oli mean, and which tense is it?

Oli is the past tense (imperfect) of the verb olla (to be).

Very roughly:

olla = to be
on = is / are
oli = was / were

So:

Elokuvan loppu on surullinen. = The end of the movie is sad.
Elokuvan loppu oli surullinen. = The end of the movie was sad.

Why is it surullinen, not surullista or something else?

Surullinen is an adjective meaning sad.

Here, the structure is:

(Subject) Elokuvan loppu
(Verb) oli
(Predicative adjective) surullinen

In this kind of “X was Y” sentence, the predicative usually appears in the nominative, agreeing with the subject in number:

Loppu oli surullinen. = The end was sad.
Loput olivat surullisia. = The endings were sad. (plural subject → plural + partitive-type predicative)

Surullista would be the partitive form and would appear in different structures (for example: Minua suretti. Se oli surullista. — I felt sad. That was sad in a more abstract sense). For this sentence, surullinen is the normal form.

Does surullinen describe the movie’s mood, or that the viewer felt sad?

Literally, surullinen describes the end itself:

Elokuvan loppu oli surullinen.
→ The ending of the movie was sad / sorrowful / tragic.

It does not directly say anything about how the viewer felt, only about the emotional quality of the ending. Of course, we usually assume a sad ending also makes the viewer feel sad, but grammatically the adjective is attached to loppu (end), not to the person.

Could this sentence also mean “The movie ended sadly”?

Not quite.

Elokuvan loppu oli surullinen.
→ The ending of the movie was sad. (adjective describing the ending, a noun)

To say “The movie ended sadly” (focusing on the manner of ending as an action), a more natural Finnish version would be:

Elokuva loppui surullisesti.
- elokuva = the movie (subject)
- loppui = ended (verb)
- surullisesti = sadly (adverb)

So your original sentence is about what kind of ending it was (a sad ending), not how the movie ended as an event.

Can you explain the structure of the whole sentence in simple terms?

Yes. You can map it almost 1:1 to English:

Elokuvan = of the movie / the movie’s (genitive)
loppu = end, ending (subject noun)
oli = was (past tense of to be)
surullinen = sad (adjective describing loppu)

So the pattern is:

[Genitive modifier] + [Noun subject] + [Past “to be”] + [Adjective predicative]
= The [NOUN] of the [THING] was [ADJECTIVE].

Exactly like: “The end of the movie was sad.”

How would the sentence change if the subject were plural, like “the endings of the movies were sad”?

You’d mark plural on the head noun and adjust the verb and adjective:

Elokuvien loput olivat surullisia.
- elokuva → elokuvien (plural genitive) = of the movies
- loppu → loput (plural subject) = endings
- oli → olivat (3rd person plural) = were
- surullisia (plural / partitive-type predicative form) = sad (describing multiple items)

So singular: Elokuvan loppu oli surullinen.
Plural: Elokuvien loput olivat surullisia.

Is there a more casual or colloquial way to say “the end of the movie was sad”?

Colloquially, Finns often say leffa instead of elokuva. For example:

Leffan loppu oli surullinen.

Here:

leffa = casual movie, flick
leffan = genitive of the movie
The rest of the structure stays the same.

In a very spoken register, you might also hear reduced forms in fast speech, but Leffan loppu oli surullinen is a natural informal version.

How do you pronounce “Elokuvan loppu oli surullinen”?

Roughly in IPA: [ˈeloˌkuʋɑn ˈlopːu ˈoli ˈsurulːinen]

Key points:

Stress is always on the first syllable of each word: E-lo-ku-van lop-pu o-li su-rul-li-nen.
Double consonants (pp, ll) are held longer: loppu [lopːu], surullinen [surulːinen].
Finnish vowels are pure and clearly pronounced:
- e as in bed (but pure),
- o like in or but shorter and rounded,
- u like oo in boot (but shorter),
- a like a in father.
Every written vowel is pronounced; there are no silent letters.