U zapisniku su opis bicikla, točna lokacija i vrijeme krađe.

Because after u meaning in, Croatian normally uses the locative case when talking about location.

• zapisnik = report / record
• u zapisniku = in the report

So -u here marks the locative singular form.

Because the subject is actually a list of three things:

• opis bicikla = description of the bicycle
• točna lokacija = exact location
• vrijeme krađe = time of the theft

Together, that makes a plural subject, so Croatian uses su (are) rather than je (is).

This is due to Croatian clitic placement. The short form su is an unstressed word, and unstressed words usually go in the second position in the sentence or clause.

So:

• U zapisniku su opis bicikla, točna lokacija i vrijeme krađe.

is more natural than:

• U zapisniku opis bicikla, točna lokacija i vrijeme krađe su.

Even though English would normally place are later, Croatian often puts short forms like su near the beginning.

Because bicikla is in the genitive case.

The pattern is:

• opis + genitive = description of ...

So:

• opis bicikla = description of the bicycle

This is very common in Croatian. English often uses of, while Croatian often uses the genitive case instead.

For the same reason: krađe is in the genitive case.

• vrijeme = time
• krađa = theft
• vrijeme krađe = time of the theft

So both bicikla and krađe are genitives that depend on the nouns before them.

Because adjectives in Croatian must agree with the noun they describe in gender, number, and case.

Here:

• lokacija is feminine singular
• so the adjective must also be feminine singular
• therefore: točna lokacija

Compare:

• točan opis = exact description
• točna lokacija = exact location
• točno vrijeme = exact time

It is understandable and grammatical, but it can sound a bit compressed or formal, almost like report language.

A fuller version might be:

• U zapisniku su navedeni opis bicikla, točna lokacija i vrijeme krađe.
  = The report includes the description of the bicycle, the exact location, and the time of the theft.

or

• U zapisniku se nalaze opis bicikla, točna lokacija i vrijeme krađe.
  = In the report there are the description of the bicycle, the exact location, and the time of the theft.

So the original sentence is fine, but it has a slightly formal, list-like feel.

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

So:

• opis bicikla can mean a description of the bicycle or the description of the bicycle
• točna lokacija can mean an exact location or the exact location

The exact meaning depends on context.

Yes. Croatian word order is more flexible than English, although not completely free.

For example, you could also say:

• Opis bicikla, točna lokacija i vrijeme krađe su u zapisniku.

That version puts more emphasis on what is in the report.

The original version:

• U zapisniku su ...

puts more emphasis on where those details are found.

So the difference is mainly about focus and style, not basic meaning.

Because in Croatian, as in English, you normally do not put a comma before the final i (and) in a simple list.

So:

• opis bicikla, točna lokacija i vrijeme krađe

is the normal punctuation.

A comma before i would usually only appear in special cases, not in an ordinary list like this.