Vidim njihovu kuću.

Vidim means I see. The subject ja (I) is not missing; it is simply omitted because Serbian usually leaves out subject pronouns when the verb ending already makes the person clear.

• vidim = I see
• ja vidim = I see, but with extra emphasis on I

So Vidim njihovu kuću. is a normal, natural sentence.

The base form is videti (in Ekavian) or vidjeti (in Ijekavian), both meaning to see.

Vidim is the 1st person singular present tense form:

• ja vidim = I see

So the sentence uses the present tense of to see.

Because kuću is in the accusative case.

The noun kuća means house in the nominative form. But in this sentence, house is the direct object of see, and direct objects in Serbian often go into the accusative.

• kuća = house (nominative)
• kuću = house (accusative)

A very common pattern is:

• feminine noun ending in -a in nominative
• changes to -u in accusative singular

So:

• kuća → kuću
• žena → ženu
• knjiga → knjigu

Because njihovu has to agree with kuću in gender, number, and case.

The noun kuća is:

• feminine
• singular
• accusative

So the possessive word must also be:

• feminine
• singular
• accusative

That is why you get:

• njihova kuća = their house (nominative)
• vidim njihovu kuću = I see their house (accusative)

So both words change together:

• njihova → njihovu
• kuća → kuću

Here it means their.

The possessive adjective njihov refers to them in the plural:

• njihov brat = their brother
• njihova kuća = their house

If you wanted his or her, you would usually use:

• njegov / njegova / njegovu = his
• njen / njena / njenu = her

So in this sentence, njihovu kuću specifically means their house.

Because Serbian does not have articles like English a/an and the.

So kuća, kuću, njihova kuća, and njihovu kuću do not include a separate word for the. Whether English translates it as a house or the house depends on context.

In this sentence, English naturally uses their house, without needing to show an article separately in Serbian.

The word order is not completely fixed. Serbian is more flexible than English because case endings show the grammatical roles.

Vidim njihovu kuću. is the most neutral order.

You can also say:

• Njihovu kuću vidim.

This still means I see their house, but it puts more emphasis on their house.

So the default order is natural and neutral, but other orders are possible for emphasis, contrast, or style.

You know it mainly from the accusative endings.

Both words show accusative singular feminine:

• njihovu
• kuću

That tells you this phrase is the direct object of the verb vidim.

So even if the word order changes, the endings still help you understand who is doing the action and what is being seen.

A useful approximate pronunciation is:

• njihovu ≈ NYEE-ho-voo

The beginning nj is pronounced like the ny sound in canyon.

So:

• nj ≈ ny
• njihovu ≈ nyee-HO-voo

This is only an approximation, but it is a good starting point for an English speaker.

A rough English-friendly approximation is:

• kuću ≈ KOO-tyoo

The letter ć is a soft sound, somewhat like a very soft ch or ty. It is softer than č.

So:

• č is harder
• ć is softer

In practice, many learners start with something like ty and refine it over time.

Because svoj is a reflexive possessive adjective, used when the possessor is the same as the subject.

Here, the subject is I:

• Vidim... = I see...

But the owners are they:

• njihovu kuću = their house

So njihovu is correct.

Compare:

• Vidim njihovu kuću. = I see their house.
• Vidim svoju kuću. = I see my own house.

So svoju would change the meaning.