Evidencijski list opisuje uočljivu oznaku po kojoj prepoznajem bicikl.

Because opisuje takes a direct object, and the direct object is normally in the accusative case.

• nominative: uočljiva oznaka = a noticeable mark
• accusative: uočljivu oznaku = a noticeable mark, as the thing being described

Both words change because the adjective must agree with the noun in gender, number, and case:

• oznaka is feminine singular
• so the adjective uočljiv must also become feminine singular accusative: uočljivu

So:

• uočljiva oznaka = subject form
• opisuje uočljivu oznaku = object form

Kojoj is the locative singular feminine form of koja.

It is used because the preposition po here requires the locative. The phrase po kojoj means something like:

• by which
• according to which
• through which
• in this sentence, more naturally: by which / from which I recognize the bicycle

Since kojoj refers back to oznaku, which is feminine singular, it must also be feminine singular.

So the logic is:

• oznaka = feminine singular noun
• po requires locative
• therefore: po kojoj

Here po kojoj means by which or according to which.

In Croatian, po often appears in expressions where English uses by, especially when talking about identifying or judging something on the basis of a feature.

So:

• oznaka po kojoj prepoznajem bicikl = the mark by which I recognize the bicycle

You can think of it literally as:

• the mark according to which I recognize the bicycle

That sounds a little stiff in English, but it helps explain the Croatian structure.

Prepoznajem is the imperfective verb form, while prepoznam is from the perfective partner.

In Croatian, aspect matters a lot:

• prepoznavati / prepoznavati or commonly prepoznavati / prepoznati as a pair
• prepoznajem = I recognize / I am able to recognize / I habitually recognize
• prepoznam = I recognize at a specific completed moment, or in certain subordinate/future-style contexts

In this sentence, the meaning is general and descriptive:

• this is the mark by which I recognize the bicycle

That kind of habitual or general present usually uses the imperfective:

• prepoznajem

Bicikl is masculine singular, but for many inanimate masculine nouns, the accusative is the same as the nominative.

So:

• nominative: bicikl
• accusative: bicikl

That is why the form does not visibly change, even though it is the direct object of prepoznajem.

Compare:

• Vidim bicikl. = I see the bicycle.
• Bicikl je crven. = The bicycle is red.

Same form, different case function.

Evidencijski list means something like:

• record sheet
• registration sheet
• log sheet
• entry sheet

The exact translation depends on context.

Word by word:

• evidencijski = relating to records, registration, or official tracking
• list = sheet, form, page, record sheet

So this sounds administrative or official. It is the kind of phrase you might see in forms, documentation, or inventory records.

It is more specific than just a mark.

• oznaka = mark, sign, label, identifying mark
• uočljiva = noticeable, visible, conspicuous, easy to notice

So uočljiva oznaka suggests a distinguishing visible feature that helps identify something.

Depending on context, it could mean:

• a visible mark
• a distinguishing mark
• a noticeable identifying feature

In this sentence, that is probably the best sense: a feature that helps identify the bicycle.

Because the pronoun kojoj agrees with oznaka, not with bicikl.

Notice the gender:

• oznaka is feminine
• bicikl is masculine

The form kojoj is feminine singular, so it must refer to oznaka.

That means the structure is:

• uočljivu oznaku
• po kojoj prepoznajem bicikl

So the sentence means:

• a noticeable mark by which I recognize the bicycle

not:

• a bicycle by which...

Yes. Croatian word order is fairly flexible, although some versions sound more natural than others.

The original order is normal and clear:

• Evidencijski list opisuje uočljivu oznaku po kojoj prepoznajem bicikl.

You could also say:

• Evidencijski list opisuje oznaku po kojoj prepoznajem bicikl.
• Po kojoj prepoznajem bicikl, evidencijski list opisuje uočljivu oznaku.

But the second version is much more marked and less neutral.

Croatian often uses word order to manage focus and emphasis, not just grammar. The original sentence sounds like standard written Croatian, especially in an official context.

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

So a noun like bicikl can mean:

• a bicycle
• the bicycle

The exact meaning depends on context.

Likewise:

• evidencijski list could mean a record sheet or the record sheet
• uočljivu oznaku could mean a noticeable mark or the noticeable mark

English must choose an article, but Croatian usually leaves that to context.

It is present tense, but in sentences like this it often has a general descriptive meaning, not just something happening right now.

So opisuje can mean:

• describes
• is describing
  but here most naturally:
• describes in a general sense

This is very common in definitions, instructions, and official documents:

• Obrazac sadrži... = The form contains...
• Pravilnik određuje... = The regulation defines...
• Evidencijski list opisuje... = The record sheet describes...

So the present tense is being used for a general factual statement.

Yes, it is a very natural pattern.

Croatian often uses:

• po + locative
• especially with verbs of identifying, judging, classifying, or recognizing

Examples of the pattern:

• Po čemu ga poznaješ? = By what do you know/recognize him?
• Po glasu je prepoznajem. = I recognize her by her voice.
• Po boji razlikujem vrste. = I distinguish the species by color.

So po kojoj prepoznajem bicikl fits a common usage:

• by which I recognize the bicycle

The sentence breaks down like this:

• Evidencijski list = subject
• opisuje = verb
• uočljivu oznaku = direct object
• po kojoj prepoznajem bicikl = relative clause describing oznaku

So the full structure is:

• The record sheet
• describes
• a noticeable mark
• by which I recognize the bicycle

This is a good example of Croatian packing a lot of information into noun phrases and relative clauses without needing articles.