Ta plava suknja je moderna.

Ta is a demonstrative adjective, and in this sentence it most naturally means that.

So ta plava suknja = that blue skirt.

Croatian does not have articles like the and a/an, so learners often look for a direct equivalent. There usually isn’t one. Instead, Croatian can be:

• more general, with no article at all
• or more specific, using words like ovaj / ta / onaj

Very roughly:

• ova = this
• ta = that (often something already known, mentioned, or identifiable)
• ona = that over there / that one

In real usage, ta can sometimes feel a bit like that and sometimes like that specific one.

Because suknja is a feminine singular noun in the nominative case, and the demonstrative has to agree with it.

Croatian demonstratives change form to match the noun’s:

• gender
• number
• case

For taj (that), the nominative singular forms are:

• taj for masculine
• ta for feminine
• to for neuter

Since suknja is feminine singular, the correct form is ta.

Because the adjective must agree with suknja.

In Croatian, adjectives change to match the noun they describe in:

• gender
• number
• case

Since suknja is feminine singular nominative, the adjective is also feminine singular nominative:

• masculine: plav
• feminine: plava
• neuter: plavo

So:

• plava suknja = blue skirt

It can mean blue, but it can also mean blonde when talking about a female person.

Examples:

• plava suknja = blue skirt
• plava žena / plava djevojka = a blonde woman / blonde girl

Here, because it describes suknja (skirt), it clearly means blue.

For the same reason as plava: adjective agreement.

Moderna is the feminine singular nominative form of modern.

Compare:

• masculine: moderan
• feminine: moderna
• neuter: moderno

Because suknja is feminine singular, the predicate adjective after je also appears in the feminine singular form:

• Suknja je moderna. = The skirt is modern.

Je is the 3rd person singular present tense of the verb biti (to be).

So:

• ja sam = I am
• ti si = you are
• on/ona/ono je = he/she/it is

In this sentence:

• Ta plava suknja je moderna.
• je = is

Croatian normally uses this verb just like English does in sentences such as X is Y.

In standard Croatian, no—you normally keep je in a sentence like this.

So:

• Ta plava suknja je moderna. = correct
• Ta plava suknja moderna. = not standard as a normal full sentence

Croatian is not like Russian, where the present-tense to be can often be omitted.

Yes, Croatian word order is more flexible than English word order, because the endings carry a lot of grammatical information.

The neutral, straightforward order here is:

• Ta plava suknja = subject
• je = verb
• moderna = complement

So:

• Ta plava suknja je moderna.

That is the most natural basic version.

Other orders are possible for emphasis, for example:

• Moderna je ta plava suknja.
• Ta suknja je plava i moderna. (if you change the structure)

But for learners, the safest default is the standard neutral order: subject + je + adjective.

Yes, they are doing different jobs, but both still agree with suknja.

• plava is an adjective directly describing the noun: the blue skirt
• moderna is a predicate adjective after je: the skirt is modern

In Croatian, both kinds of adjectives agree with the noun.

So with suknja (feminine singular), you get:

• plava suknja
• suknja je moderna

That’s why both adjectives end in -a here.

Very often, yes.

Many Croatian nouns ending in -a are feminine, including:

• suknja = skirt
• žena = woman
• kuća = house

So suknja is feminine, and that affects the forms around it:

• ta suknja
• plava suknja
• suknja je moderna

However, -a is not an absolute rule for every noun in the language, so it’s best thought of as a very common pattern, not a guarantee.

A simple approximate pronunciation for an English speaker is:

Tah PLAH-vah SOOK-nyah yeh moh-DEHR-nah

A few useful notes:

• j in Croatian sounds like English y in yes
• je sounds roughly like yeh
• nj in suknja is like the ny sound in canyon
• Croatian spelling is quite phonetic, so words are usually pronounced much as they are written

It is completely normal and neutral.

Ta plava suknja je moderna. sounds like standard Croatian and works in:

• conversation
• exercises
• everyday description
• written standard language

It is not especially formal or especially slangy. It’s just a plain, natural descriptive sentence.