Ilia domo estas proksime de la stacidomo.

Ili means they, while ilia means their.

• ili = they
• ilia = their

In this sentence, ilia describes domo (house), so you need the possessive form: their house.

Actually, it does match in number, but not in case here.

Domo is singular, so ilia is also singular in form. In Esperanto, possessive words like mia, via, ilia behave like adjectives and can take -j and -n if needed:

• ilia domo = their house
• iliaj domoj = their houses
• ilian domon = their house (as a direct object)

In your sentence, domo is singular and not accusative, so ilia stays ilia.

Because domo is not the direct object. It is the subject of the sentence.

The structure is:

• Ilia domo = subject
• estas = is
• proksime de la stacidomo = near the station

The accusative -n is usually used for a direct object, and there is no direct object here.

Good question. Both forms exist, but they are used differently.

• proksima = an adjective, meaning near and describing a noun
• proksime = an adverb, meaning nearby / near, describing the situation or location

In Ilia domo estas proksime de la stacidomo, proksime works adverbially: Their house is near the station.

You could also say:

• Ilia domo estas proksima al la stacidomo.

That uses the adjective proksima instead.

So Esperanto often allows two patterns:

• esti proksime de...
• esti proksima al...

Both are natural.

This is a common thing learners notice.

In practice:

• proksime de = near, close to
• proksima al = near, close to

So:

• La domo estas proksime de la lernejo.
• La domo estas proksima al la lernejo.

Both mean roughly the same thing.

You should mostly learn them as fixed patterns:

• adverb + de
• adjective + al

That will sound natural.

Stacidomo is a compound word:

• staci- = station-related idea, from stacio
• domo = house/building

So stacidomo literally means something like station building, and in normal use it means train station / railway station.

Esperanto often builds words this way, so compounds are very common.

Because it means the station.

Esperanto has only one definite article: la. It does not change for gender, number, or case except that the noun itself may change.

So:

• la stacidomo = the station
• la domoj = the houses

There is no separate word for a/an in Esperanto. If you want an indefinite sense, you usually just leave out the article.

Estas is the present tense of esti, meaning to be.

So:

• mi estas = I am
• ili estas = they are
• la domo estas = the house is

In this sentence, estas links the subject (Ilia domo) to the location expression (proksime de la stacidomo).

Yes, Esperanto word order is fairly flexible, because endings show grammatical roles.

For example, these are possible:

• Ilia domo estas proksime de la stacidomo.
• Proksime de la stacidomo estas ilia domo.

The first is the most neutral and straightforward. The second gives more emphasis to the location.

Even though Esperanto allows flexibility, learners should usually prefer the basic order first, because it sounds clear and natural.

A simple pronunciation guide is:

EE-lee-ah DOH-moh ESS-tahs prohk-SEE-meh deh lah stah-chee-DOH-moh

A few useful points:

• stress is always on the second-to-last syllable:
  • I-li-a
  • DO-mo
  • ES-tas
  • prok-SI-me
  • sta-ci-DO-mo
• c is pronounced like ts
• j sounds like English y
• vowels are always clear and consistent

So stacidomo is pronounced roughly stah-tsee-doh-moh.

Yes, it is natural and correct.

A very common alternative is:

• Ilia domo estas proksima al la stacidomo.

Both are standard Esperanto. The version with proksime de may feel a little more like an adverbial location phrase, while proksima al uses an adjective. For most learners, both are worth recognizing.

Normally ilia means their, referring to more than one person, because it comes from ili = they.

If you want his, her, or its, you would usually use:

• lia = his
• ŝia = her
• ĝia = its

So ilia domo normally means their house, not his house or her house.

It actually does use de, which often corresponds to of / from / by, depending on context.

In this phrase, proksime de is just the normal Esperanto pattern for near. You should think of it as a fixed combination rather than translating each word separately from English.

So instead of trying to match English word-for-word, it is better to learn:

• proksime de = near
• malproksime de = far from