Learn Hardcore Croatian: Na poslu naš tim često razgovara s novim šefom. - At work our team often talks with the new boss.

na + locative is common for:
- workplaces and institutions: na poslu, na fakultetu, na sudu (at court)
- events: na sastanku (at a meeting), na zabavi (at a party)
u + locative is more about being inside something physically:
- u uredu – in the office
- u zgradi – in the building

So na poslu is the standard fixed phrase for at work, not u poslu.
You could hear u poslu in special contexts, but then it would mean something like in the middle of some work / in the business itself, not “at your workplace.”

Why is the verb razgovara (3rd person singular) and not plural, even though tim is a group of people?

In Croatian, verbs agree with the grammatical form of the subject, not with the “real-world” number of people it contains.

tim (team) is a singular noun (like class, family in English)
Therefore it takes a singular verb:
- Naš tim često razgovara… – Our team often talks…

If you changed the subject to a clear plural, the verb would be plural:

Naši kolege često razgovaraju s novim šefom. – Our colleagues often talk with the new boss.

Could the word order be different? For example, can I say Naš tim često razgovara na poslu s novim šefom?

Yes, Croatian word order is flexible, and several orders are grammatically correct. For example:

Na poslu naš tim često razgovara s novim šefom.
Neutral: first set the place (na poslu), then say what the team often does there.
Naš tim često razgovara s novim šefom na poslu.
Similar meaning; na poslu is now added as extra information at the end.
Na poslu često naš tim razgovara s novim šefom.
Puts extra emphasis on često and naš tim – more “at work it is often our team that talks with the new boss”.

All of these are possible. The version you were given is natural and fairly neutral. Word order mainly changes emphasis, not basic meaning.

Why is it razgovara s and not razgovara sa?

The basic preposition is s (with), and it takes the instrumental case:

razgovarati s nekim – to talk with someone

Croatian uses s or sa mainly for pronunciation reasons:

s is default: s novim šefom, s kolegom, s bakom
sa is used:
- before words starting with s, z, š, ž or certain clusters, to make speech easier:
  - sa sestrom, sa ženom, sa školom
- when speakers want it to sound clearer or more natural in fast speech

Here s novim šefom is perfectly standard and natural; sa novim šefom is also possible in everyday speech, but s is the “default” form.

Why do we say s novim šefom and not something like sa novog šefa? Which case is that?

The preposition s/sa meaning with requires the instrumental case.

In the phrase s novim šefom:

nov (new) → novim = instrumental singular masculine
šef (boss) → šefom = instrumental singular masculine
s novim šefom = with the new boss

So the pattern is:

s/sa + instrumental = with
- s prijateljem – with a (male) friend
- s prijateljicom – with a (female) friend
- s novim šefom – with the new (male) boss

A form like sa novog šefa would be genitive after sa in a different meaning (from the new boss, not with the new boss), and it doesn’t fit the verb razgovarati here.

What is the difference between razgovarati s nekim, pričati s nekim, and govoriti s nekim?

They overlap a lot, and all three can mean to talk with someone, but there are typical nuances:

razgovarati s nekim
- implies a two-way conversation, often a bit more neutral or formal
- razgovarati o poslu – talk about work
pričati s nekim
- very common in everyday speech
- can feel a bit more informal, story-like, or chatty
- pričati s prijateljem – chat with a friend, tell stories
govoriti s nekim
- slightly more formal; also means to speak (a language):
  - govorim engleski – I speak English
- govoriti s novim šefom – to talk/speak with the new boss (perfectly OK, maybe a bit more formal or neutral).

In your sentence, razgovarati s novim šefom is very natural: have conversations with / talk with the new boss.

What does često do here, and where can it go in the sentence?

Često means often and is an adverb of frequency.

In your sentence:

Na poslu naš tim često razgovara s novim šefom.
= At work our team often talks with the new boss.

Typical positions for često:

before the verb: naš tim često razgovara (most common)
after the verb: naš tim razgovara često (possible; can sound a bit more emphatic or stylistic)
before the subject (for emphasis): Često naš tim razgovara s novim šefom.

All are grammatically fine; subject + često + verb is the most neutral.

How would I say this in the past tense: “At work, our team often talked with the new boss”?

Use the past tense of razgovarati (imperfective) with je as the auxiliary:

Na poslu je naš tim često razgovarao s novim šefom.

Breakdown:

je – auxiliary (3rd person singular of biti, to be)
razgovarao – past participle, masculine singular (agrees with tim, which is grammatically masculine singular)

If the subject were clearly plural, the participle would be plural:

Na poslu su naši kolege često razgovarali s novim šefom.
At work, our colleagues often talked with the new boss.

If the boss is a woman, how does s novim šefom change?

For a female boss, you usually say šefica (feminine form of šef). Then everything has to agree in gender and case:

s novom šeficom – with the new (female) boss

Changes:

novim → novom (instrumental singular feminine)
šefom → šeficom (instrumental singular feminine)

So the whole sentence becomes:

Na poslu naš tim često razgovara s novom šeficom.

Can I just say Na poslu tim često razgovara s novim šefom without naš? Does it change the meaning?

Yes, you can omit naš:

Na poslu tim često razgovara s novim šefom.

Meaning:

With naš tim – our team, specifically identified as belonging to “us.”
With tim alone – the team, more general, or a team already understood from context.

So naš simply adds possession (our). Omitting it doesn’t change the grammar, only the nuance.