Lik je važan u filmu.

Je is the 3rd person singular present form of biti (to be).

So the sentence structure is:

• lik = subject
• je = is
• važan = predicate adjective (important)

Croatian usually needs this form of to be in sentences like this:

• Lik je važan. = The character is important.

One useful thing to notice: je is a clitic, so it normally appears in the second position in the sentence.

Because važan has to agree with lik in gender, number, and case.

• lik is masculine singular
• so the adjective must also be masculine singular
• therefore: važan

Compare:

• lik je važan → masculine singular
• uloga je važna → feminine singular
• mjesto je važno → neuter singular

This agreement is very important in Croatian.

Lik is in the nominative singular, because it is the subject of the sentence.

You can think of it as the basic dictionary form here.

• lik = nominative singular
• it answers the question Who/what is important?
• answer: lik

Because u can take different cases depending on meaning.

Here, u filmu means in the film/movie, so it expresses location, not motion.
When u means in/inside/at a place, it usually takes the locative case.

So:

• film = nominative
• u filmu = locative

Compare:

• u filmu = in the film
• u film would suggest motion into something, but with film that would not normally make sense here

A helpful rule:

• u + locative = location
• u + accusative = movement into

Example:

• On je u kući. = He is in the house.
• On ide u kuću. = He is going into the house.

In this sentence, lik means character, especially a fictional character in a film, book, or story.

That said, lik can also mean other things depending on context, for example:

• a figure or shape
• colloquially, a guy/person, sometimes with a slightly informal tone

But in Lik je važan u filmu, the natural interpretation is character.

Croatian does not use articles like English a/an/the.

So lik by itself can mean:

• a character
• the character

The exact meaning depends on context.

For example, if you are already talking about one specific character, then lik may be understood as the character. If you are speaking more generally, it may feel more like a character.

Croatian speakers rely on context much more than English does for this.

Yes. Croatian word order is fairly flexible, although not completely free.

Lik je važan u filmu is a neutral, natural order.

But other orders are possible for emphasis, for example:

• U filmu je lik važan.
• Važan je lik u filmu.

These do not all sound equally neutral, and some are more marked or poetic than others. The main idea is that Croatian often changes word order to show focus or emphasis.

One thing stays important: the clitic je usually stays in the second position.

Yes, often you can.

• važan = important
• bitan = important / essential / relevant

So:

• Lik je važan u filmu.
• Lik je bitan u filmu.

Both can work, but there can be a slight nuance:

• važan often sounds like important/significant
• bitan can feel a bit more like crucial or relevant

In everyday speech, both are common.

No, they are not usually the same.

• u filmu = in the film/movie as part of its story or content
• na filmu often means on film, in cinema, or captured on film, depending on context

For a character appearing within the story, u filmu is the natural choice:

• Lik je važan u filmu.

You make it negative by changing je to nije:

• Lik nije važan u filmu.

So:

• je = is
• nije = is not

This is one of the most common negative patterns in Croatian.

When u means in and expresses location, yes:

• u filmu = in the film

That is because the noun film is masculine singular, and its locative singular form is filmu.

Other examples with the same pattern:

• u gradu = in the city
• u razredu = in the classroom

So film → filmu is a normal masculine noun pattern in the locative singular.