U zoološkom vrtu smo vidjeli žirafu i zebru pokraj velike ograde.

Because u can take different cases depending on meaning:

• u + accusative = motion into somewhere
• u + locative = location in somewhere

Here the sentence describes where we saw the animals, not movement into the zoo, so Croatian uses the locative:

• u zoološkom vrtu = in the zoo

Both words change because zoološki vrt is a two-word noun phrase:

• zoološki → zoološkom
• vrt → vrtu

So the whole phrase is in the locative singular.

It is the locative singular.

Why?

• The preposition u meaning in/at requires the locative when it expresses location.
• vrt is a masculine noun, so its locative singular is vrtu.
• The adjective zoološki must agree with the noun in gender, number, and case, so it becomes zoološkom.

So:

• zoološki vrt = nominative
• u zoološkom vrtu = locative

That is how the past tense is usually formed in Croatian.

It uses:

• the present tense of biti (to be) as an auxiliary
• plus the l-participle of the main verb

Here:

• smo = we are / we have as the auxiliary for we
• vidjeli = past participle of vidjeti (to see)

So smo vidjeli means we saw / we have seen.

This is the normal Croatian past tense pattern:

• sam vidio/vidjela = I saw
• si vidio/vidjela = you saw
• je vidio/vidjela = he/she saw
• smo vidjeli/vidjele = we saw

Because the participle agrees with the subject in number and, in the plural, often also in gender.

• vidjeli = masculine plural, or a mixed-gender group
• vidjele = feminine plural

Since the subject is only understood, not stated, smo vidjeli usually suggests:

• we as a mixed group, or
• we if gender is unknown, or
• we if the speaker uses the masculine/mixed form

If the speakers were all female, you would normally say:

• U zoološkom vrtu smo vidjele žirafu i zebru...

Because Croatian often drops subject pronouns when they are not needed.

The verb already tells you the person and number:

• smo = we

So mi is unnecessary unless you want emphasis or contrast.

Compare:

• Smo vidjeli is not used by itself, because the auxiliary needs proper placement in a full sentence.
• Mi smo vidjeli... = We saw... with emphasis on we
• U zoološkom vrtu smo vidjeli... = neutral, natural sentence

Croatian does this much more often than English.

Because they are direct objects, so they go into the accusative case.

The verb vidjeti (to see) takes a direct object.
Both žirafa and zebra are feminine nouns ending in -a, and in the accusative singular they change to -u:

• žirafa → žirafu
• zebra → zebru

So:

• žirafa = nominative

• vidjeli žirafu = accusative

• zebra = nominative
• vidjeli zebru = accusative

This is a very common pattern for feminine nouns.

Because the preposition pokraj requires the genitive case.

So both the adjective and noun must be in genitive singular feminine:

• velika ograda = nominative, a big fence
• pokraj velike ograde = genitive, next to a big fence

Breakdown:

• velika → velike
• ograda → ograde

The adjective must agree with the noun, so both change together.

Pokraj means beside, next to, or by.

In this sentence:

• pokraj velike ograde = next to the big fence

A very common alternative is pored, which also takes the genitive:

• pored velike ograde

Both are natural. In many contexts they are nearly interchangeable.

Because smo is a clitic, and Croatian clitics usually appear in the second position of the sentence or clause.

Here the first unit is:

• U zoološkom vrtu

Then the clitic comes:

• smo

So the sentence is:

• U zoološkom vrtu smo vidjeli...

This is very typical Croatian word order.

You could also say:

• Vidjeli smo žirafu i zebru u zoološkom vrtu.

That is also correct, but the original sentence puts the location first for emphasis or topic.

Yes. Croatian word order is more flexible than English because the cases show grammatical roles.

Possible versions include:

• U zoološkom vrtu smo vidjeli žirafu i zebru pokraj velike ograde.
• Žirafu i zebru smo vidjeli u zoološkom vrtu pokraj velike ograde.
• Vidjeli smo žirafu i zebru pokraj velike ograde u zoološkom vrtu.

But not every version sounds equally natural in every context. The original is a very normal way to begin with the setting:

• In the zoo, we saw...

The main restriction is that clitics like smo tend to stay in second position.

No. Croatian does not use articles like English a/an and the.

So:

• žirafu can mean a giraffe or the giraffe
• zebru can mean a zebra or the zebra
• velike ograde can mean a big fence or the big fence

The exact meaning depends on context.

That is why a single Croatian sentence can correspond to several slightly different English versions.

Yes. Zoološki vrt is the standard expression for zoo.

Literally it means zoological garden, which is similar to older or formal expressions in some other languages. But in Croatian it is the normal everyday term.

So:

• zoološki vrt = zoo
• u zoološkom vrtu = in the zoo

Because i simply means and, just as in English.

So:

• žirafu i zebru = a giraffe and a zebra

Croatian does not need any extra marker here. Both nouns are direct objects, so both are in the accusative.

Grammatically, it most naturally describes the location of the seeing event:

• we saw a giraffe and a zebra next to a big fence

In practice, that usually also implies that the animals were near the fence. Croatian, like English, can leave a little room for interpretation in a phrase like this.

If you wanted to make the structure clearer, you could rephrase:

• U zoološkom vrtu smo pokraj velike ograde vidjeli žirafu i zebru.
• U zoološkom vrtu smo vidjeli žirafu i zebru koje su bile pokraj velike ograde.

The second version explicitly says the animals were next to the fence.

The dictionary form is vidjeti, meaning to see.

From that verb you get forms like:

• vidim = I see
• vidiš = you see
• vidio / vidjela = saw, masculine/feminine singular
• vidjeli / vidjele = saw, plural

So when learning vocabulary, you would normally memorize:

• vidjeti = to see

Then u would take the accusative, not the locative.

For example:

• U zoološki vrt smo ušli. = We entered the zoo.

Compare:

• u zoološkom vrtu = in the zoo, location, locative
• u zoološki vrt = into the zoo, direction, accusative

This location-vs-direction contrast with u is very important in Croatian.