Prirodno svjetlo može smanjiti naprezanje očiju.

Because it is agreeing with svjetlo, which is a neuter singular noun.

In Croatian, adjectives change their form to match the noun in:

• gender
• number
• case

Here:

• svjetlo = neuter singular
• so prirodan becomes prirodno

A quick comparison:

• prirodan zrak = natural air (masculine)
• prirodna voda = natural water (feminine)
• prirodno svjetlo = natural light (neuter)

It is in the nominative singular, because it is the subject of the sentence.

The subject is the thing doing the action:

• Prirodno svjetlo = natural light
• može smanjiti = can reduce

So natural light is the thing that can reduce something.

This is a very common Croatian structure:

• moći = to be able to / can
• smanjiti = to reduce

When Croatian uses a modal verb like moći (can), it is followed by an infinitive.

So:

• može = can
• smanjiti = reduce

Together:

• može smanjiti = can reduce

This is similar to English:

• can reduce
• not can reduces

Because the subject prirodno svjetlo is third person singular.

The verb moći changes depending on the subject:

• ja mogu = I can
• ti možeš = you can
• on/ona/ono može = he/she/it can

Since svjetlo is grammatically it, Croatian uses:

• može

So:

• Prirodno svjetlo može... = Natural light can...

It is in the accusative singular, because it is the direct object of the verb smanjiti.

The sentence is reducing what?

• naprezanje = strain

So it is the object.

A useful detail: naprezanje is a neuter noun, and many neuter nouns have the same form in:

• nominative singular
• accusative singular

So here naprezanje looks the same, even though its role is the object.

Because očiju is the genitive plural form of oko (eye).

In naprezanje očiju, Croatian literally says something like:

• strain of the eyes

That means the second noun often goes into the genitive.

So:

• oko = eye
• oči = eyes (nominative plural)
• očiju = of the eyes (genitive plural)

This is a very common Croatian pattern:

• bol u leđima = pain in the back
• boja očiju = color of the eyes
• naprezanje očiju = eye strain

Yes, oko is somewhat irregular.

Its singular is:

• oko = eye

But its plural uses a different stem:

• oči = eyes

And then:

• očiju = of the eyes

So this is one of those nouns you usually just have to learn as a set:

• oko
• oči
• očiju

Yes, it is a very natural and common expression for eye strain.

The noun naprezanje comes from the idea of straining or putting under effort.
So naprezanje očiju literally means:

• straining of the eyes

In natural English we usually say:

• eye strain

So even though the grammar is different, the Croatian expression is normal and idiomatic.

This is about aspect, which is very important in Croatian verbs.

• smanjiti = perfective
• smanjivati = imperfective

Here, smanjiti is natural because it means to reduce in the sense of producing a result.

So:

• može smanjiti naprezanje očiju = can reduce eye strain

If you used smanjivati, it would sound more like:

• reducing repeatedly
• reducing over time
• being in the process of reducing

In general explanations of what something is capable of doing, Croatian often prefers the perfective verb after moći.

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

The neutral order here is:

• Prirodno svjetlo može smanjiti naprezanje očiju.

But other orders are possible for emphasis, for example:

• Naprezanje očiju može smanjiti prirodno svjetlo.

That still means roughly the same thing, but it may sound more marked or emphasize a different part of the sentence.

For a learner, the original version is the best neutral, standard word order.

Roughly, svjetlo sounds like:

• SVYEH-tloh

A few notes:

• svj is a consonant cluster, so it may feel difficult at first
• je here sounds roughly like ye
• the t and l are both clearly pronounced

You can think of it approximately as:

• svyet-lo

Not exact English, but close enough to help.

Roughly:

• OH-chee-yoo

Breakdown:

• o = like o in more (shorter)
• č = ch as in church
• i = ee
• ju = yoo

So:

• očiju ≈ OH-chee-yoo

Not exactly.

• prirodno svjetlo = natural light
• dnevno svjetlo = daylight

Prirodno svjetlo is broader. It usually means light from natural sources, especially sunlight, as opposed to artificial indoor lighting.

So in many contexts the English translation may feel very close to daylight, but the Croatian phrase itself is more literally natural light.

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

So:

• svjetlo can mean light, the light, or sometimes a light, depending on context

In this sentence:

• Prirodno svjetlo = natural light

English requires an article system, but Croatian does not. Learners usually need to get used to understanding definiteness from context instead.