Moj sin želi nacrtati sovu koja sjedi iznad vrata štale.

Because sovu is the accusative singular form, and it is the direct object of nacrtati.

• sova = an owl (dictionary form, nominative)
• sovu = an owl (as the object)

In this sentence, the son wants to draw the owl, so owl is what the action is done to.

• Moj sin želi nacrtati sovu = My son wants to draw an owl

This is very common in Croatian: the noun changes form depending on its role in the sentence.

Because koja is the subject of the relative clause.

The relative clause is:

• koja sjedi iznad vrata štale = which is sitting above the barn door

Here, the owl is the one doing the sitting, so the relative pronoun must be in the nominative:

• koja = which / who (feminine singular nominative)

If the owl were the object inside that clause, you would expect koju instead.

So the structure is:

• sovu = object of nacrtati
• koja = subject of sjedi

Even though both refer to the same owl, they belong to different parts of the sentence and therefore can have different cases.

Nacrtati is the perfective verb, while crtati is the imperfective one.

• crtati = to be drawing / to draw in a general or ongoing sense
• nacrtati = to draw, with the idea of completing the drawing

So:

• želi crtati = wants to draw, wants to be drawing
• želi nacrtati = wants to draw it and finish it

In this sentence, nacrtati suggests a completed result: the son wants to make a drawing of an owl.

This aspect difference is very important in Croatian and often has no exact one-word equivalent in English.

Because Croatian commonly uses a conjugated verb plus an infinitive after verbs like want, can, must, like, and similar verbs.

So:

• želi = wants
• nacrtati = to draw

Together:

• želi nacrtati = wants to draw

This works much like English want + to + verb, except Croatian uses the infinitive form directly, without a separate word equivalent to to.

Because moj must agree with sin.

• sin is masculine singular
• so the possessive adjective must also be masculine singular nominative

That gives:

• moj sin = my son

Compare:

• moja kći = my daughter
• moje dijete = my child

So the form of my changes depending on the gender, number, and case of the noun it describes.

Because vrata is a noun that is normally used in the plural form in Croatian, even when it refers to a single door.

So:

• vrata = door / doors, depending on context

This is one of those nouns that behaves differently from English. Learners often notice that it looks plural, and that is correct grammatically.

In this sentence:

• iznad vrata štale = above the barn door

Even though English uses singular door, Croatian naturally uses vrata.

Because iznad normally requires the genitive case.

So after iznad you expect a genitive form:

• iznad vrata = above the door
• iznad kuće = above the house
• iznad stola = above the table

With vrata, the genitive form is also vrata, so it looks the same as the basic form. That can be confusing, but the case is still genitive because of the preposition iznad.

Because it depends on vrata and means of the barn.

• štala = barn
• štale = of the barn

So:

• vrata štale = the door of the barn / the barn door

This is a very common Croatian structure: one noun in the genitive describes another noun.

Examples:

• krov kuće = the roof of the house
• vrata sobe = the door of the room
• prozor auta = the car window

It is a relative clause describing sovu.

The main part of the sentence is:

• Moj sin želi nacrtati sovu = My son wants to draw an owl

Then Croatian adds more information about that owl:

• koja sjedi iznad vrata štale = which is sitting above the barn door

So the full sentence means:

• My son wants to draw an owl that is sitting above the barn door.

The relative clause helps identify which owl is meant.

Normally, no. In standard Croatian, the relative pronoun is needed.

So you say:

• sovu koja sjedi...

not simply:

• sovu sjedi...

The word koja links the noun sovu with the descriptive clause sjedi iznad vrata štale.

English sometimes allows shorter reduced forms like the owl sitting above the door, but Croatian usually keeps the full relative structure in a sentence like this.

Yes, Croatian word order is fairly flexible, but this version is the most neutral and natural.

This order gives:

• Moj sin = topic / subject
• želi nacrtati = verb phrase
• sovu = object
• koja sjedi... = description of the object

You could change the order for emphasis, but the basic meaning would stay the same because case endings show the grammatical roles.

For example, a different order might sound more marked or literary, but the original sentence is the most straightforward choice for everyday neutral Croatian.

A simple guide:

• ž sounds like the s in measure
• j sounds like English y
• c sounds like ts
• sj is pronounced together, somewhat like sy in careful speech

So approximately:

• želi ≈ ZHEH-lee
• nacrtati ≈ NA-tsr-ta-tee
• sjedi ≈ SYEH-dee

These are only rough English-based approximations, but they can help at the start.

Yes, sova is feminine, and that matters a lot.

Because it is feminine singular, related words must match it where appropriate:

• sova = nominative
• sovu = accusative
• koja = feminine singular nominative relative pronoun, referring back to sova

So the feminine gender of sova is the reason you get koja rather than koji or koje.

By itself, it most naturally suggests an owl that is sitting there in the situation being described.

• koja sjedi = which is sitting

However, depending on context, Croatian present tense can sometimes also describe a more general characteristic. So in the right context, it could refer to the owl that sits above the barn door as a usual habit.

If you wanted to make the ongoing, right-now idea especially clear, context usually does that rather than a different verb form.