Главный герой улыбается в конце фильма.

Not necessarily. In Russian, главный герой is a very common way to say main character or protagonist.

So even if the character is not morally heroic, Russians can still call them главный герой. In everyday discussion of books and films, this is completely normal.

Because главный is an adjective, and it has to agree with герой.

Here герой is:

• masculine
• singular
• nominative case

So the adjective also has to be:

• masculine
• singular
• nominative

That is why you get главный герой.

Улыбается is the 3rd person singular present tense form of улыбаться.

Breakdown:

• улыбаться = to smile
• улыбается = he/she smiles, is smiling

It is 3rd person singular because the subject, главный герой, is one person.

Because the dictionary form of the verb is улыбаться, not улыбать.

The -ся ending is very common in Russian and often comes from an older reflexive meaning, but in many verbs it is just part of the normal verb. In this case, улыбаться simply means to smile.

So you should learn улыбаться as a whole verb.

A useful extra point:

• улыбаться = to smile
• улыбнуть(ся) exists in some contexts, but улыбаться is the standard everyday verb

Because Russian, like English, often uses the present tense for plot summaries.

So when talking about what happens in a book, film, or story, Russian often says things like:

• герой умирает
• она понимает правду
• главный герой улыбается в конце фильма

This is the same idea as English film-summary language: At the end of the movie, the main character smiles.

If you were talking about your experience of watching the film, you could also use the past tense in a different sentence.

There are two different case changes happening here.

1. в конце

   • The preposition в here means something like in/at
   • With this meaning, it takes the prepositional case
   • конец becomes конце

2. фильма

   • конец often takes a dependent noun in the genitive
   • конец чего? = the end of what?
   • фильм becomes фильма

So:

• конец = end
• в конце = at/in the end
• в конце фильма = at the end of the film

Because в конце is the normal expression for at the end of a time period, story, film, text, event, and so on.

Examples:

• в конце фильма = at the end of the film
• в конце книги = at the end of the book
• в конце года = at the end of the year

На конце usually sounds physical, like on the end/tip of something.

So for a film or story, в конце is the natural choice.

Yes. Russian word order is more flexible than English word order.

The sentence as given:

• Главный герой улыбается в конце фильма.

is a neutral, natural order.

But you could also say:

• В конце фильма главный герой улыбается.

That version puts more focus on at the end of the film.

The basic meaning stays the same, but the emphasis can shift depending on word order and context.

Russian has no articles, so there is no direct equivalent of the or a/an.

Whether something is definite or indefinite is understood from context.

Here, главный герой already sounds naturally specific, because in a film there is usually a particular main character being discussed. So English translates it as the main character even though Russian does not use a separate word for the.

A natural stress pattern is:

Гла́вный геро́й улыба́ется в конце́ фи́льма.

A rough English-style pronunciation guide:

• Гла́вный = GLAHV-nyy
• геро́й = gee-ROY
• улыба́ется = oo-ly-BA-ye-tsa
• в конце́ = v kon-TSYE
• фи́льма = FEEL-ma

One useful pronunciation note: endings like -тся and -ться are often pronounced roughly like -ца in normal speech, even though they are spelled with тс.