Oznaka za prtljagu je u ručnoj prtljazi.

A word-for-word breakdown is:

• oznaka = tag, label, marker
• za = for
• prtljagu = luggage, baggage
• je = is
• u = in
• ručnoj = hand-, carry-on
• prtljazi = luggage, baggage

So the structure is basically:

• oznaka za prtljagu = luggage tag
• je u ručnoj prtljazi = is in the carry-on luggage

Because za here means for, and in this use it takes the accusative case.

The noun is:

• prtljaga = nominative singular
• prtljagu = accusative singular

So:

• oznaka za prtljagu = a tag for luggage

This is a very common pattern in Croatian:
noun + za + accusative = something intended for something.

Because the sentence is doing two different things:

1. oznaka za prtljagu names the object: the luggage tag
2. u ručnoj prtljazi tells you where it is: in the carry-on luggage

So even though English might also repeat luggage, the two instances have different grammatical jobs:

• za prtljagu = for luggage
• u ručnoj prtljazi = in carry-on luggage

Because u meaning in takes the locative case when it shows a location.

The basic phrase is:

• ručna prtljaga = hand luggage / carry-on luggage

But after u for location, it becomes:

• u ručnoj prtljazi

Both words change because the adjective and noun must agree:

• ručna → ručnoj
• prtljaga → prtljazi

They are both feminine singular locative.

Ručna prtljaga is the normal travel term for:

• hand luggage
• carry-on luggage
• carry-on baggage

Here ručna comes from the idea of hand. It does not mean luggage that is somehow handmade. It is a fixed travel expression.

Je is the 3rd person singular of biti (to be) and it behaves like a clitic in Croatian.

Clitics usually go in the second position of the sentence or clause. That often means after the first whole phrase, not necessarily after the first single word.

So:

• Oznaka za prtljagu | je | u ručnoj prtljazi

This word order is normal and natural.

Because u means in / inside, while na usually means on / onto / at.

So:

• u ručnoj prtljazi = in the carry-on luggage
• na ručnoj prtljazi would suggest something like on the carry-on luggage

If the tag were attached to the outside of the bag, a phrase with na could make sense. But this sentence says the tag is inside the carry-on luggage.

No. U can take either:

• locative for location: in
• accusative for movement into: into

In this sentence, the tag is already located somewhere, so Croatian uses the locative:

• u ručnoj prtljazi = in the carry-on luggage

If you were talking about putting it there, you would use the accusative:

• Stavljam oznaku u ručnu prtljagu. = I am putting the tag into the carry-on luggage.

Here is the case breakdown:

• oznaka = nominative singular
  It is the subject.

• za prtljagu = accusative singular after za
  This is part of the phrase luggage tag.

• u ručnoj prtljazi = locative singular after u
  This tells the location.

So the sentence is useful because it shows the same noun, prtljaga, in two different cases:

• prtljagu = accusative
• prtljazi = locative

Because Croatian does not have articles like a or the.

So oznaka can mean:

• a tag
• the tag

Which one is meant depends on context. In this sentence, English might naturally say the luggage tag, but Croatian simply uses oznaka without an article.

No. Oznaka is a broader word that can mean:

• label
• mark
• designation
• tag
• sign

In this airport/travel context, luggage tag is the natural meaning of oznaka za prtljagu.

So the exact English translation depends on context, but here tag is the best fit.

Yes, a few:

• č in ručnoj sounds like ch in church
• ž in prtljazi sounds like the s in measure
• j is pronounced like English y
• lj is a special Croatian sound, roughly similar to lli in million for many learners

A rough pronunciation guide would be:

• oznaka ≈ oz-NA-ka
• prtljagu ≈ prt-LYA-gu
• ručnoj ≈ ROOCH-noy
• prtljazi ≈ prt-LYA-zi

The cluster prtlj- is especially hard at first, so learners often need a bit of practice with prtljaga.