Tiu filmo estas timiga.

Tiu means that.

In tiu filmo, it works like a demonstrative determiner: it points to a specific movie.

• tiu filmo = that movie / that film
• tiu by itself can also mean that one

A useful contrast is:

• ĉi tiu filmo = this movie
• tiu filmo = that movie

Because tiu already makes the noun definite.

In Esperanto, you normally do not use la together with tiu.

• tiu filmo = that movie
• not la tiu filmo

So tiu already does the job of identifying which movie you mean.

Because -o is the normal noun ending in Esperanto.

So:

• film- = the root
• filmo = film / movie

This is one of the most regular parts of Esperanto grammar:

• nouns end in -o
• adjectives end in -a
• adverbs end in -e

For example:

• filmo = movie
• bona = good
• bone = well

Yes. Estas is the present tense of esti, which means to be.

So:

• estas = is / am / are

Unlike English, Esperanto verbs do not change depending on the subject.

• mi estas = I am
• vi estas = you are
• li estas = he is
• tiu filmo estas = that movie is
• ili estas = they are

So estas stays the same every time in the present tense.

Literally, timiga means something like fear-causing.

It is built from:

• tim- = fear
• -ig- = to cause, make
• -a = adjective ending

So timiga means:

• scary
• frightening
• fear-inducing

That is why Tiu filmo estas timiga means That movie is scary.

Because tima and timiga mean different things.

• tima = afraid, fearful
• timiga = scary, causing fear

So:

• tima homo = a fearful person
• timiga filmo = a scary movie

If you said Tiu filmo estas tima, it would sound like That movie is afraid, which is usually not what you mean.

Because it is an adjective describing filmo.

In Esperanto, adjectives end in -a.

Here, timiga is a predicate adjective after estas, but it is still an adjective, so it keeps the -a ending.

• filmo = noun
• timiga = adjective describing the noun

If it were an adverb, it would end in -e, but that would mean something different.

• timige = in a scary way

So here timiga is correct because the sentence is describing what kind of thing the movie is.

Because this sentence has no direct object.

Tiu filmo is the subject, not the object, so it stays without -n.

Also, after estas, Esperanto normally uses the basic form for the description:

• Tiu filmo estas timiga.

So there is no reason for -n here.

You would expect -n on a direct object, for example:

• Mi vidas tiun filmon. = I see that movie.

In your sentence, nothing is being directly acted on, so no -n appears.

You would say:

Ĉi tiu filmo estas timiga.

Here:

• ĉi tiu = this
• tiu = that

So the difference is:

• Ĉi tiu filmo estas timiga. = This movie is scary.
• Tiu filmo estas timiga. = That movie is scary.

It would be:

Tiuj filmoj estas timigaj.

Here all the relevant words change to plural:

• tiu → tiuj = that → those
• filmo → filmoj = movie → movies
• timiga → timigaj = scary → scary (plural adjective)

Esperanto adjectives agree with the nouns they describe in number, so both filmoj and timigaj get -j.

It can mean either, depending on context.

In many cases, filmo is used where English speakers might say either film or movie.

So this sentence could be understood as:

• That film is scary
• That movie is scary

Both are natural translations.