Learn Hardcore Croatian: Sutra ću isključiti mobitel prije sastanka. - Tomorrow I will turn off the phone before the meeting.

Sutra – adverb meaning tomorrow; it tells us when the action happens.
ću – future tense auxiliary, 1st person singular of htjeti (to want), used here to form Future I: I will.
isključiti – infinitive, perfective verb meaning to turn off / switch off.
mobitel – noun, masculine, meaning mobile phone / cell phone, in the accusative (direct object).
prije – preposition meaning before, which always takes the genitive case.
sastanka – genitive singular of sastanak (meeting), required by the preposition prije → “before the meeting”.

Why is there no “ja” (I) in the sentence? Can I say Ja ću isključiti mobitel?

Croatian normally drops subject pronouns, because the verb form already shows the person:

ću isključiti tells us it is 1st person singular (I will turn off), so ja is not needed.

You can say:

Ja ću isključiti mobitel sutra prije sastanka.

This is grammatically correct, but ja is usually added only for emphasis or contrast, e.g.:

Ja ću isključiti mobitel, ali ti ga ostavi upaljenim.
I will turn off my phone, but you leave yours on.

Why is ću after Sutra, and not before or at the end? Are other word orders possible?

In Croatian, short forms like ću (called clitics) usually go in second position in the clause. In this sentence:

Sutra (1st position)
ću (2nd position – clitic)
isključiti mobitel prije sastanka (rest of the clause)

Other natural orders include:

Sutra ću isključiti mobitel prije sastanka.
Mobitel ću sutra isključiti prije sastanka.
Sutra ću prije sastanka isključiti mobitel.

You generally cannot put ću at the very end by itself:

✗ Sutra isključiti mobitel prije sastanka ću. (incorrect)

How is the future tense formed here? Why do we use ću + infinitive?

Croatian Future I is often made with:

present of htjeti (ću, ćeš, će, …) + infinitive

For ja (I):

ja ću isključiti – I will turn off

Some full conjugation examples:

ja ću isključiti – I will turn off
ti ćeš isključiti – you (sg.) will turn off
on / ona / ono će isključiti – he / she / it will turn off
mi ćemo isključiti – we will turn off
vi ćete isključiti – you (pl.) will turn off
oni / one / ona će isključiti – they will turn off

Colloquially, when the infinitive is right after the auxiliary, people often drop the final -i:

Isključit ću mobitel. (more common spelling than Isključiti ću)

Why is it isključiti and not isključivati? What’s the difference?

Croatian verbs come in aspect pairs:

isključiti – perfective (focus on a single completed action)
isključivati – imperfective (focus on repeated / ongoing action)

In this sentence we talk about one specific action completed in the future:

Sutra ću isključiti mobitel prije sastanka.
→ Tomorrow I will (once, completely) turn off my phone before the meeting.

If you said:

Sutra ću isključivati mobitel prije sastanka.

it would sound like you repeatedly turn it off before (each) meeting – a habit, not one specific occasion. That’s why isključiti (perfective) is the natural choice.

Why is it prije sastanka and not prije sastanak? Which case is used after prije?

The preposition prije (before) always takes the genitive case.

sastanak – nominative (dictionary form, “meeting”)
sastanka – genitive singular (“of the meeting”)

So:

prije sastanka = before the meeting (literally: before of-meeting)

Using nominative:

✗ prije sastanak

is ungrammatical. You must use genitive: prije sastanka.

What about mobitel – which gender is it, and which case is used here?

mobitel is a masculine noun.
In this sentence, it is the direct object of isključiti, so it is in the accusative singular.

For masculine inanimate nouns, nominative and accusative often look the same:

Nominative: mobitel je na stolu. – The phone is on the table.
Accusative: Isključujem mobitel. – I’m turning off the phone.

So mobitel here is accusative, even though it looks like nominative.

Could I change the word order to Sutra ću prije sastanka isključiti mobitel or Isključit ću mobitel sutra prije sastanka? Does the meaning change?

Yes, these are all natural and keep the same basic meaning:

Sutra ću isključiti mobitel prije sastanka.
Sutra ću prije sastanka isključiti mobitel.
Isključit ću mobitel sutra prije sastanka.

Differences:

All versions still mean “Tomorrow I will turn off my phone before the meeting.”
The word order mainly affects emphasis and rhythm, not basic meaning.
- Placing sutra at the beginning slightly emphasizes tomorrow.
- Moving prije sastanka earlier can highlight before the meeting a bit more.

The important rules you must keep:

ću stays in (roughly) second position among the main sentence elements.
Preposition + noun stay together: prije sastanka cannot be split.

Can I use present tense instead of future, like Sutra isključujem mobitel prije sastanka?

You can use the present in Croatian to talk about a planned future action, especially if it’s scheduled or certain:

Sutra isključujem mobitel prije sastanka.

This sounds like a firm plan or routine, similar to English “Tomorrow I’m turning off my phone before the meeting.”

However:

Future I (ću + infinitive) – neutral, simple future: a decision or plan.
Present for future – often a bit more planned / scheduled / definite.

Both are correct; Sutra ću isključiti… is the most straightforward “plain future” form.

Is isključiti mobitel the only way to say “turn off the phone”? Are there synonyms?

There are several common options:

isključiti mobitel – to switch off the phone (very common, neutral).
ugasiti mobitel – literally to extinguish, to put out; also very common in everyday speech for turning off any device.
spremiti mobitel – to put the phone away (not exactly turn off, but often used when you’re about to stop using it).

In your sentence, you could also say:

Sutra ću ugasiti mobitel prije sastanka.

The meaning is practically the same in everyday conversation.