Ta plava jakna dobro stoji uz crne hlače.

Because they all agree with each other in gender, number, and case.

• jakna = jacket
• It is a feminine singular noun
• In this sentence, it is in the nominative singular because it is the subject

So the demonstrative and adjective must match it:

• ta = that (feminine singular nominative)
• plava = blue (feminine singular nominative)
• jakna = jacket (feminine singular nominative)

This kind of agreement is very important in Croatian.

Ta means that.

It is the feminine singular form of the demonstrative pronoun:

• taj = that (masculine)
• ta = that (feminine)
• to = that (neuter)

Since jakna is feminine, Croatian uses ta.

So:

• ta jakna = that jacket

Because the adjective has to agree with the noun.

Jakna is feminine singular, so blue must also be in the feminine singular form:

• plav = basic dictionary form, usually masculine
• plava = feminine singular
• plavo = neuter singular
• plavi can appear in some masculine forms, but not with jakna

So:

• plava jakna = correct
• plavi jakna = incorrect

Yes, stojiti/stajati is related to standing, and stoji literally means stands or is standing. But in this sentence, it is being used idiomatically.

With clothes and appearance, dobro stoji means things like:

• looks good
• suits
• goes well
• fits well stylistically

So Ta plava jakna dobro stoji uz crne hlače means the blue jacket matches the black trousers well.

Croatian often uses verbs in ways that sound more physical or concrete than English.

Because dobro is an adverb, not an adjective here.

It describes the verb stoji:

• dobro stoji = it looks good / it goes well

Compare:

• dobra jakna = a good jacket → adjective describing the noun
• jakna dobro stoji = the jacket looks good / goes well → adverb describing the verb

A very common pattern in Croatian is:

• adjective: dobar / dobra / dobro
• adverb: dobro

Here uz means something like:

• with
• together with
• next to
• in fashion contexts, goes with

So:

• stajati uz nešto
• ići uz nešto

can both mean to go well with something

In this sentence:

• uz crne hlače = with black trousers

It does not mean physical attachment here; it means stylistic matching.

It is accusative plural, because the preposition uz normally takes the accusative.

So:

• uz + accusative

The noun is:

• hlače = trousers / pants

And the adjective must agree:

• crne hlače = black trousers

For feminine plural nouns like this, the nominative plural and accusative plural often look the same, so even though the form is crne hlače, the case here is accusative because of uz.

Hlače is normally used as a plural-only noun in Croatian, just like:

• trousers
• pants
• scissors

in English.

So even when you mean one item of clothing, Croatian still uses the plural form:

• ove hlače = these trousers / these pants
• crne hlače = black trousers

This is very normal and something learners just have to get used to.

No. Another very common expression is ići uz.

For example:

• Ta plava jakna ide uz crne hlače.
• Ta plava jakna dobro stoji uz crne hlače.

Both can mean that the jacket matches the trousers.

A rough difference:

• ići uz often focuses on matching
• dobro stajati uz can sound a bit more like looking good together

In real life, both are natural.

Because Croatian does not use articles like English the and a/an.

English says:

• the blue jacket
• a blue jacket

Croatian simply says:

• plava jakna

If you want to be more specific, Croatian often uses:

• a demonstrative: ta plava jakna = that blue jacket
• context
• word order
• intonation

So Croatian expresses definiteness differently from English.

Yes, Croatian word order is more flexible than English, because case endings show the grammatical relationships.

The sentence:

• Ta plava jakna dobro stoji uz crne hlače.

is a very natural neutral order.

You may also hear different orders for emphasis, such as:

• Uz crne hlače ta plava jakna dobro stoji.
• Ta plava jakna uz crne hlače dobro stoji.

But for a learner, the original version is the safest and most natural to use.

A simple approximate pronunciation is:

• Ta plava yak-na dobro stoyee ooz tsrne hlah-cheh

A few useful notes:

• j is pronounced like English y
  • jakna sounds like yakna
• stoji sounds roughly like stoyi
• uz sounds like ooz
• č in hlače sounds like ch in church
• cr in crne can be tricky for English speakers because there is no vowel between c and r

A more careful breakdown:

• Ta = tah
• plava = plah-vah
• jakna = yahk-nah
• dobro = doh-broh
• stoji = stoh-yee / stoyee
• uz = ooz
• crne = tsr-neh
• hlače = hlah-cheh

You simply put ne before the verb:

• Ta plava jakna ne stoji dobro uz crne hlače.

That means:

• That blue jacket does not go well with black trousers.

This is a very common way to negate verbs in Croatian:

• stoji = it goes / it looks
• ne stoji = it does not go / it does not look right

Here are the main dictionary forms:

• ta → from the demonstrative set taj, ta, to
• plava → dictionary form plav = blue
• jakna → jakna = jacket
• dobro → from dobar = good
• stoji → dictionary verb stajati or sometimes linked with stojati, depending on grammar treatment
• uz → preposition uz
• crne → dictionary form crn = black
• hlače → hlače = trousers / pants

This is useful because Croatian dictionaries usually list adjectives and many pronouns in a masculine base form.