Potpisnik čeka u javnobilježničkom uredu.

Yes. Potpisnik means signer or signatory, depending on context.

It comes from potpis (signature) and refers to a person who signs or is signing a document. In legal or official contexts, signatory is often the best English equivalent.

Čeka is the 3rd person singular present tense of the verb čekati (to wait).

So:

• ja čekam = I wait / I am waiting
• ti čekaš = you wait / you are waiting
• on/ona/ono čeka = he/she/it waits / is waiting

Here, the subject is potpisnik, which is singular, so čeka is the correct form.

It can mean both.

Croatian present tense often covers both:

• he waits
• he is waiting

The exact meaning depends on context. In this sentence, English would most naturally say is waiting, but grammatically Croatian just uses the ordinary present tense.

Because after u meaning in, Croatian normally uses the locative case for location.

The base noun is:

• ured = office

Its locative singular form is:

• uredu = in the office

The adjective must match the noun in case, number, and gender:

• javnobilježnički ured = notary office
• u javnobilježničkom uredu = in the notary office

So both words change:

• javnobilježnički → javnobilježničkom
• ured → uredu

It is locative singular.

Why?

• u
  • location = usually locative
• The noun ured is masculine singular
• The adjective javnobilježnički agrees with it

So:

• nominative: javnobilježnički ured
• locative: u javnobilježničkom uredu

Javnobilježnički is an adjective meaning notarial or relating to a notary public.

It comes from javni bilježnik, which means notary public.

So:

• javni bilježnik = notary public
• javnobilježnički ured = notary office / notarial office

Croatian often forms these longer institutional adjectives in this way.

Because Croatian often creates a single adjective from a two-word expression.

So:

• javni bilježnik = notary public
• javnobilježnički = notarial / belonging to a notary public

This is very common in formal or administrative language. English often uses a phrase, while Croatian may prefer one long adjective.

Yes, often you could, but the meaning shifts slightly.

• u javnobilježničkom uredu = in the notary’s office
• kod javnog bilježnika = at the notary’s / with the notary

Both can work in many real situations.
u ... uredu focuses more on the physical place, while kod ... often focuses more on being at someone’s place or in someone’s care/service.

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

So potpisnik can mean:

• a signer
• the signer

And u javnobilježničkom uredu can mean:

• in a notary office
• in the notary office

Context tells you which meaning is intended.

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

The neutral order here is:

• Potpisnik čeka u javnobilježničkom uredu.

But other orders are possible for emphasis, for example:

• U javnobilježničkom uredu potpisnik čeka.
• Čeka potpisnik u javnobilježničkom uredu.

These do not necessarily change the basic meaning, but they can change emphasis or sound more marked. The original sentence is the most straightforward and neutral.

No. Croatian usually does not require a subject pronoun if the subject is already clear.

Here, the subject is explicitly stated as potpisnik, so there is no reason to add on.

In fact, adding on would usually sound unnecessary unless you want contrast or emphasis:

• On čeka u javnobilježničkom uredu. = He is waiting in the notary office.
  This would emphasize he.

Yes, potpisnik is grammatically masculine.

A feminine form is:

• potpisnica

So you could say:

• Potpisnica čeka u javnobilježničkom uredu. = The female signatory is waiting in the notary office.

Then the verb čeka stays the same, because present tense verb forms do not change for gender.

From its form.

• singular nominative: ured
• singular locative: uredu
• plural locative: uredima

So u javnobilježničkom uredu clearly means in the office / in a notary office in the singular.

If it were plural, it would be:

• u javnobilježničkim uredima = in notary offices