Na konferenciji imamo susret s novim šefom i kratko predavanje.

Both na and u can translate to at/in, but they’re used with different kinds of events and locations.

• na is used with many events / activities:

  • na konferenciji – at the conference
  • na sastanku – at the meeting
  • na predavanju – at the lecture
  • na koncertu – at the concert

• u is used more with physical spaces / interiors:

  • u uredu – in the office
  • u sobi – in the room
  • u školi – in the school

A konferencija is treated as an event, so Croatians say na konferenciji, not u konferenciji.

Konferenciji is in the locative singular case.

• Nominative (dictionary form): konferencija – a/the conference
• Locative singular (after na, u when meaning at/in a place/event): konferenciji

For most feminine nouns ending in -cija (like konferencija, organizacija, prezentacija), the locative singular ending is -i:

• o konferenciji – about the conference
• na prezentaciji – at the presentation
• u organizaciji – in the organization

So na konferenciji literally means on/at the conference, with konferenciji in the locative.

Croatian often uses the present tense to talk about scheduled future events, very similar to English:

• English: Tomorrow we have a meeting. (present form have, future meaning)
• Croatian: Sutra imamo sastanak.

In your sentence:

• Na konferenciji imamo susret…
  → At the conference we have a meeting…
  (It’s understood this is the program of the conference, i.e. future.)

You could say:

• Na konferenciji ćemo imati susret… or
• Na konferenciji imat ćemo susret…

but this sounds more like you’re focusing on the fact that at some point you will have it. For announced schedules or programs, present tense (imamo) is the most natural choice.

Both can be translated as meeting, but the nuance is different:

• susret

  • literally: encounter, meeting (of people)
  • more neutral or slightly more social / general
  • often used for:
    • diplomatic or official encounters: susret predsjednika (a meeting of presidents)
    • a first-time or notable meeting: prvi susret s novim šefom

• sastanak

  • more like meeting / appointment in the business / work sense
  • e.g. poslovni sastanak – business meeting
  • imamo sastanak s klijentom – we have a meeting with a client

In this sentence, susret s novim šefom emphasizes the idea of meeting (getting to know) the new boss, not just a regular work meeting.

Both s and sa mean with. Sa is basically a variant used for ease of pronunciation.

General idea:

• Use s by default:

  • s tobom – with you
  • s prijateljem – with a friend
  • s novim šefom – with the new boss

• Use sa when s would be hard to pronounce, typically:

  • before certain consonant clusters or words starting with s, š, z, ž:
    • sa psom (with the dog) is easier than s psom
    • sa sestrom often sounds more natural than s sestrom
    • sa svim – with all

Here novim šefom starts with n, which is easy after s, so s novim šefom is perfectly smooth and preferred.

Note: s/sa here takes the instrumental case, which leads to the next question.

Novim šefom is in the instrumental singular case, required by the preposition s/sa when it means with.

• Nominative: novi šef – the new boss
• Instrumental: s novim šefom – with the new boss

Agreement:

• šef is masculine singular (ending in a consonant).
• In the masculine singular instrumental, the endings are:
  • adjectives: -im → novim
  • nouns: -om → šefom

So you get:

• (s) novim šefom – with the new boss, adjective and noun both in masculine instrumental singular.

Predavanje is a neuter noun in Croatian.

• Nominative singular: predavanje – (a) lecture
• Neuter adjectives in nominative singular end in -o (or -e).

So:

• kratko predavanje – a short lecture
  
  • kratko (short) – neuter singular adjective form
  • predavanje – neuter singular noun

If you wanted the plural, it would be:

• Nominative plural: predavanja – lectures
• Adjective (neuter plural): kratka

So:

• kratka predavanja – short lectures

In the original sentence, we are talking about one lecture, so kratko predavanje is correct.

Kratko can be both:

1. Adjective (neuter singular):

   • agrees with a neuter noun:
     • kratko predavanje – a short lecture
     • kratko putovanje – a short trip

2. Adverb (how something is done, like briefly):

   • On kratko govori. – He speaks briefly.

In kratko predavanje, kratko is an adjective, agreeing with neuter predavanje. It’s not an adverb in this sentence.

Yes, word order in Croatian is relatively flexible, and your variant is grammatically fine:

• Na konferenciji imamo kratko predavanje i susret s novim šefom.

The difference is mainly in emphasis / flow:

• Original: …susret s novim šefom i kratko predavanje.
  – feels like the meeting with the new boss is the first highlighted item.

• Your version: …kratko predavanje i susret s novim šefom.
  – now the short lecture comes first in the listener’s mind.

Both are natural; you just choose which element you want to present first.

Croatian has no articles (no words like a/an or the).

• susret can mean:
  • a meeting, the meeting, or just meeting in general.
• kratko predavanje can mean:
  • a short lecture or the short lecture.

Definiteness (a vs. the) is understood from context:

• If you’re talking about the official program of a specific conference, a native speaker will naturally interpret:
  • Na konferenciji imamo susret s novim šefom i kratko predavanje.
    as At the conference we have a/the meeting with the new boss and a/the short lecture, where both are specific planned events.

If you want to make something especially clear, you add more description, not an article, for example:

• Imamo jedan susret – we have one meeting (emphasizing number).
• Imamo baš taj susret – we have that exact meeting.

But in normal speech, you rely on context, not on articles.

Yes, you can say Mi imamo susret…, but mi is usually omitted unless you want emphasis.

• Croatian is a pro-drop language: the verb ending already shows the subject.
  • imamo → we have (mi is understood)

So:

• Na konferenciji imamo susret… – neutral, normal.
• Mi na konferenciji imamo susret… – emphasizes we, e.g. we (as opposed to others) have a meeting at the conference.

In most neutral statements, you’d say it the way it appears in your sentence, without the mi.