Appena arriva il relatore, inizia la sessione plenaria.

Here appena means as soon as.

That is an important point, because appena can also mean just / just now in other sentences, for example:

• Ho appena finito = I just finished

But in Appena arriva il relatore, inizia la sessione plenaria, it introduces a time clause, so it means as soon as.

Italian often uses the present tense to talk about the near future, especially when the sequence of events is clear from context.

So Appena arriva il relatore, inizia la sessione plenaria is perfectly natural Italian for a future situation.

You could also say:

• Appena arriverà il relatore, inizierà la sessione plenaria

That version uses the future tense and is also correct. The present-tense version often sounds a bit more immediate and natural in everyday Italian.

Italian is a pro-drop language, which means subject pronouns are often omitted when the verb ending already shows the person.

• arriva = he/she arrives
• inizia = it/he/she begins

In this sentence, Italian does not need lui or essa because the meaning is clear from context.

Also, in the second clause, the subject is actually stated explicitly: la sessione plenaria.

The subject of inizia is la sessione plenaria.

So the structure is:

• inizia = begins
• la sessione plenaria = the plenary session

Italian often allows the verb to come before the subject, especially in narrative or formal styles. So:

• Inizia la sessione plenaria
• La sessione plenaria inizia

Both are correct. The first version is a little more stylistically marked and often sounds smoother in this kind of sentence.

Yes. That is also correct.

The difference is mostly one of word order and emphasis:

• Appena arriva il relatore, inizia la sessione plenaria puts the time condition first
• La sessione plenaria inizia appena arriva il relatore starts with the main event

Both mean the same thing.

Il relatore uses the definite article because it refers to a specific, identifiable person: the speaker that both speaker and listener already know about in that context.

If you said un relatore, it would sound more like a speaker, meaning any speaker or an unspecified one.

In conference or meeting contexts, il relatore usually means the scheduled speaker / presenter.

Relatore can mean different things depending on context, but here it most naturally means:

• speaker
• presenter
• sometimes lecturer

In academic, conference, or institutional settings, relatore often refers to the person giving a talk or presenting a report.

A useful thing to notice is that relatore ends in -e, but it is still masculine here:

• il relatore
• plural: i relatori

The feminine form is usually la relatrice.

Because adjectives in Italian must agree with the noun in gender and number.

• sessione is feminine singular
• so the adjective must also be feminine singular
• therefore: plenaria

So:

• la sessione plenaria
• plural: le sessioni plenarie

If the noun were masculine singular, the adjective would be plenario.

The comma is very normal here because the sentence begins with a subordinate time clause:

• Appena arriva il relatore, ...

When this kind of clause comes first, Italian often uses a comma to separate it from the main clause. It improves readability and sounds natural in writing.

In very short informal writing, people may sometimes omit it, but the comma is a good standard choice.

No. In this sentence, appena is followed by the indicative, which is the normal choice for a time clause referring to a real event.

So:

• Appena arriva il relatore... is correct

Not the subjunctive.

This is different from certain conjunctions or expressions that trigger the subjunctive. Here the speaker is simply describing when something happens.

Yes, and that is very common for learners.

Appena can mean:

• as soon as, when followed by a clause of time
• just / just now, in other contexts

Compare:

• Appena arriva il relatore, inizia la sessione plenaria = As soon as the speaker arrives, the plenary session begins
• Il relatore è appena arrivato = The speaker has just arrived

So the context tells you which meaning is intended.

It is pronounced roughly ap-PEH-na.

A few useful points:

• the stress falls on pe
• the pp is a real double consonant in Italian, so it is held a little longer than a single p
• appena is not pronounced like English a pena

Paying attention to double consonants is important in Italian, because they can change meaning and make your pronunciation sound much more natural.