Si arribo tard a la reunió, la professora començarà sense mi.

In Catalan, for a real future condition, the verb after si usually goes in the present indicative, not the future.

So:

• Si arribo tard... = If I arrive late...
• la professora començarà... = the teacher will start...

This pattern is very common:

• Si tinc temps, t’ajudaré. = If I have time, I’ll help you.
• Si plou, no sortirem. = If it rains, we won’t go out.

So the structure is:

• si + present
• main clause in the future (or sometimes another appropriate tense)

Arribo is the 1st person singular present indicative of arribar (to arrive).

So:

• arribar = to arrive
• arribo = I arrive

Catalan often uses the present tense in conditional clauses where English also uses the present:

• Si arribo tard... = If I arrive late...

Not if I will arrive late.

Catalan often omits subject pronouns because the verb ending already shows who the subject is.

• arribo already means I arrive
• so jo is usually unnecessary

You can add jo for emphasis or contrast:

• Si jo arribo tard, la professora començarà sense mi, però si tu arribes tard, t’esperarà.

But in a neutral sentence, leaving it out is more natural.

Tard is the normal Catalan word for late in this kind of sentence.

• arribar tard = to arrive late

Catalan does not need a form like English lately or an -ly adverb here.

Examples:

• Vaig arribar tard. = I arrived late.
• Sempre arriba tard. = He/She always arrives late.

So tard is the standard word to use after verbs like arribar.

A la reunió means to the meeting.

Breakdown:

• a = to / at
• la = the
• reunió = meeting

So:

• arribar a la reunió = to arrive at the meeting / to the meeting

Catalan uses the article here, just like English does in the meeting.

Also note:

• reunió is a feminine noun
• that is why it takes la

Yes. La professora refers to a female teacher/professor.

Compare:

• el professor = the male teacher/professor
• la professora = the female teacher/professor

So this sentence specifically tells you the teacher is a woman.

Començarà is the future tense, 3rd person singular, from començar (to begin / start).

So:

• començarà = he/she/it will begin / will start

In the sentence:

• la professora començarà sense mi = the teacher will start without me

The accent in començarà shows the stress falls on the last syllable:

• co-men-ça-rà

It is a normal written accent in the future form.

After a preposition like sense (without), Catalan uses a stressed pronoun, not the normal subject pronoun.

So:

• mi = me
• tu = you
• ell / ella = him / her
• nosaltres = us
• vosaltres = you all
• ells / elles = them

That is why you say:

• sense mi = without me

not:

• sense jo

Compare:

• amb mi = with me
• per mi = for me
• sense mi = without me

Yes, sense mi is completely natural and standard.

You may also hear more explicit versions depending on context, but sense mi is the normal straightforward form.

For example:

• Van marxar sense mi. = They left without me.
• La classe començarà sense mi. = The class will start without me.

The comma separates the conditional clause from the main clause:

• Si arribo tard a la reunió, = If I arrive late to the meeting,
• la professora començarà sense mi. = the teacher will start without me.

This is very common when the if-clause comes first.

If the order is reversed, the comma is often omitted:

• La professora començarà sense mi si arribo tard a la reunió.

Both versions are correct.

Yes. You can also say:

• La professora començarà sense mi si arribo tard a la reunió.

This means the same thing.

The version with si first is often a bit clearer and more natural when presenting the condition first, but both are fine.

Yes. Reunió is stressed on the last syllable:

• re-u-ni-ó

The written accent on ó marks that stress.

This is useful because Catalan spelling often uses accents to show where the stress goes.

It can mean both begin and start.

• La professora començarà can be translated as:
  • The teacher will begin
  • The teacher will start

In everyday English, start often sounds more natural here, but both are correct translations.

It usually expresses a real or possible future situation.

• Si arribo tard... = If I arrive late...

This is not a contrary-to-fact idea like If I arrived late... in English, which can sometimes sound more hypothetical depending on context.

So the Catalan sentence suggests a realistic condition: if that happens, then the teacher will start without me.

Not in this sentence.

After si, when you are talking about a real future condition, Catalan normally uses the indicative, not the subjunctive.

So the correct form is:

• Si arribo tard...

not:

• Si arribi tard...

The subjunctive is used in other structures, but not in this basic if + real condition pattern.