Rupa za odvod čuva korijen biljke.

A word-by-word breakdown is:

• rupa = hole
• za = for
• odvod = drainage / outflow / drain
• čuva = protects / preserves / keeps safe
• korijen = root
• biljke = of the plant

So the structure is roughly:

• Rupa za odvod = a drainage hole / hole for drainage
• čuva = protects
• korijen biljke = the plant’s root / the root of the plant

Because biljke is in the genitive singular.

In Croatian, possession or the idea of of is often shown with the genitive case:

• biljka = plant (nominative)
• korijen biljke = root of the plant / the plant’s root

So biljke answers the question whose root?
It is the root of the plant.

This is very common in Croatian:

• list biljke = the leaf of the plant
• boja zida = the color of the wall
• vrata kuće = the door of the house

Here korijen is in the accusative singular because it is the direct object of čuva.

The verb čuvati means to protect / to guard / to preserve, and the thing being protected goes in the accusative:

• čuva korijen = protects the root

A useful detail: korijen is a masculine inanimate noun, and for many masculine inanimate nouns, the accusative singular looks the same as the nominative singular.

So:

• nominative: korijen
• accusative: korijen

That is why the form does not change.

Here za means for, and it expresses purpose.

So:

• rupa za odvod = a hole for drainage
• more naturally in English: a drainage hole

After za, Croatian often uses the accusative case.
In this phrase, odvod is masculine inanimate, and its accusative singular is the same as the nominative, so it still appears as odvod.

This pattern is common:

• čaša za vodu = glass for water
• torba za knjige = bag for books
• mjesto za odmor = place for rest

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

So rupa can mean:

• a hole
• the hole

and the exact meaning depends on context.

Likewise:

• korijen biljke can mean the root of the plant or sometimes just a plant root, depending on the situation.

English requires articles, but Croatian usually leaves that information to context.

You know mainly from the case and the verb agreement.

• rupa is in the nominative singular, which is the usual case for the subject
• čuva is 3rd person singular, matching a singular subject
• korijen is functioning as the direct object

So the sentence structure is:

• Rupa za odvod = subject
• čuva = verb
• korijen biljke = object

Even though Croatian word order is flexible, the case system helps show who is doing the action and who is receiving it.

Čuva is the 3rd person singular present tense of the verb čuvati.

Basic forms:

• čuvati = to protect / to keep / to guard
• čuvam = I protect
• čuvaš = you protect
• čuva = he/she/it protects
• čuvamo = we protect
• čuvate = you (plural/formal) protect
• čuvaju = they protect

In this sentence, the subject rupa is singular, so the verb is čuva.

It can mean several related things, depending on context:

• protects
• guards
• keeps safe
• preserves

In this sentence, protects is probably the most natural translation.
The idea is that the drainage hole helps prevent water problems, so it protects the plant’s root.

Yes. Croatian word order is more flexible than English word order because cases show grammatical roles.

The neutral order here is:

• Rupa za odvod čuva korijen biljke.

But other orders are possible for emphasis, for example:

• Korijen biljke čuva rupa za odvod.
• Čuva korijen biljke rupa za odvod.

These alternatives are grammatically possible, but they may sound marked, literary, or emphasize a different part of the sentence.

For most learners, the original order is the safest and most natural.

Yes, they matter a lot in Croatian.

The nouns here are:

• rupa — feminine
• odvod — masculine
• korijen — masculine
• biljka — feminine

Gender affects:

• adjective endings
• pronouns
• some case endings
• sometimes verb agreement in past forms and participles

In this present-tense sentence, the main visible effects are in the noun forms and case patterns.

A few sounds may be unfamiliar to English speakers:

• č in čuva sounds roughly like ch in church, but usually harder and cleaner
• j in korijen and biljke sounds like English y in yes
• lj in biljke is a special Croatian sound, similar to a soft ly sound
• r in rupa and korijen is trilled or tapped, not the English r

Very rough pronunciation help:

• Rupa ≈ ROO-pa
• čuva ≈ CHOO-va
• korijen ≈ KO-ree-yen
• biljke ≈ BEEL-lyke (very approximate)

Yes. It is a very natural Croatian way to express purpose with a noun phrase.

Croatian often uses:

• noun + za + noun

to mean a noun used for some purpose.

So:

• rupa za odvod = hole for drainage
• natural English translation: drainage hole

This is similar to how Croatian says:

• četka za kosu = hairbrush / brush for hair
• čaša za vino = wine glass
• prostor za igru = space for اللعب / play area — more naturally, play area

Not necessarily. In Croatian, just like in English, the present tense can describe:

• something happening now
• a general fact
• a regular function
• a scientific or practical truth

Here it most likely describes a general function:

• A drainage hole protects the plant’s root.

So it means this is what a drainage hole does, not only what it is doing at this exact moment.