Uz tanjur uvijek stavim i papirnati ubrus.

Uz here means by, next to, alongside, together with in a physical sense.

So Uz tanjur means something like:

• by the plate
• next to the plate
• with the plate

In Croatian, uz normally takes the accusative case. That is why the noun after it is in accusative.

Because tanjur is a masculine inanimate noun, and in Croatian the accusative singular of masculine inanimate nouns is usually the same as the nominative singular.

So:

• nominative: tanjur
• accusative: tanjur

That is why after uz you still see tanjur.

A useful comparison:

• vidim stol = I see a table
• vidim psa = I see a dog

Here stol stays the same because it is inanimate, while pas changes because it is animate.

Because Croatian often leaves out subject pronouns when they are already clear from the verb form.

Stavim means I put because the ending -im shows 1st person singular.

So:

• stavim = I put
• ja stavim = I put, but with extra emphasis on I

In a neutral sentence, ja is usually unnecessary.

This is a question of aspect, which is very important in Croatian.

• staviti → perfective
• stavljati / stavljam → imperfective

Stavim presents the action as a complete act: each time, I put one there, and the action is done.

With uvijek (always), Croatian can naturally use a perfective present form to mean something like:

• Whenever I set it out, I put a paper napkin too.
• I always add a paper napkin.

If you said stavljam, that would sound more like a general ongoing habit or process:

• Uz tanjur uvijek stavljam i papirnati ubrus.

That is also possible, but stavim feels very natural when you mean a repeated completed action.

Here i means also / too, not just and.

So:

• stavim i papirnati ubrus = I also put a paper napkin
• I put a paper napkin too

This is very common in Croatian: i can mean also when it appears before the word or phrase being added.

Compare:

• Kavu i čaj = coffee and tea
• Stavim i čaj = I put tea too / I also add tea

Papirnati ubrus is the direct object of stavim, so it is in the accusative singular.

Because ubrus is also masculine inanimate, its accusative singular looks the same as the nominative singular:

• nominative: papirnati ubrus
• accusative: papirnati ubrus

The adjective papirnati agrees with ubrus in:

• gender: masculine
• number: singular
• case: accusative

And since masculine inanimate accusative looks like nominative, the adjective stays in the same-looking form too.

Yes, Croatian word order is fairly flexible.

This sentence starts with Uz tanjur to set the scene first: as for the plate / with the plate / next to the plate.

Then:

• uvijek = always
• stavim = I put
• i papirnati ubrus = also a paper napkin

Other word orders are possible, for example:

• Uvijek stavim i papirnati ubrus uz tanjur.
• I papirnati ubrus uvijek stavim uz tanjur.

They are not all identical in emphasis, though.

The given version sounds natural and highlights uz tanjur early, as the thing the napkin goes with.

Because Croatian has no articles like English a/an and the.

So papirnati ubrus can mean:

• a paper napkin
• the paper napkin

The exact choice in English depends on context.

In this sentence, English would usually say a paper napkin, because it sounds like a general habit rather than a specific already-mentioned napkin.

Because uz and s/sa do not mean the same thing.

• uz tanjur = by the plate / next to the plate / together with the plate
• s tanjurom = with the plate in the sense of accompanied by the plate

When talking about where something is placed on a table, uz is the natural choice because it refers to position next to something.

If you used s tanjurom, it would sound more like the napkin somehow comes with the plate as an accompanying item, not specifically that it is placed next to it.

Yes, ubrus can have a few related meanings depending on context.

It can refer to:

• a napkin
• a table napkin
• sometimes a cloth or similar item

But papirnati ubrus very clearly means paper napkin.

So in this sentence there is no real ambiguity.

It describes a general habit.

The key word is uvijek = always.

So the sentence means something like:

• I always put a paper napkin by the plate too.
• Whenever I do this, I also add a paper napkin.

Even though stavim is a present-tense form of a perfective verb, with uvijek it naturally refers to a repeated habitual action, not just one single future event.