Per Capodanno, si ricordi di arrivare presto, perché dopo le otto c’è molta gente.

Here Per Capodanno means something like for New Year’s / for the New Year celebration.

A few nuances:

• Capodanno literally refers to New Year’s Day, but in everyday use it can also refer to the New Year period or celebration, depending on context.
• In this sentence, because it talks about arriving early and crowds after 8, it most likely refers to the New Year celebration rather than just the calendar day itself.

So Per Capodanno is setting the occasion: as for New Year’s, / for New Year’s, ...

Si ricordi is the formal imperative of ricordarsi.

The speaker is addressing someone politely, using the Lei form. In Italian, commands to Lei use the present subjunctive form:

• (Lei) si ricordi = please remember
• informal tu version: ricordati
• plural voi version: ricordatevi

So this sentence is speaking to one person in a formal/polite way.

Here si is not the impersonal si. It is part of the reflexive verb ricordarsi.

So:

• ricordarsi di fare qualcosa = to remember to do something
• si ricordi = remember / please remember

This is different from impersonal constructions like:

• In Italia si mangia bene = In Italy, people eat well

In your sentence, si belongs to the person being addressed politely.

Because with the formal imperative (Lei), object and reflexive pronouns normally go before the verb:

• si ricordi
• mi dica
• si accomodi

By contrast, with the informal tu imperative, the pronoun is usually attached to the end:

• ricordati
• dimmi
• accomodati

So:

• formal: si ricordi
• informal: ricordati

Because ricordarsi is commonly followed by di + infinitive when it means remember to do something.

Pattern:

• ricordarsi di + infinitive

Examples:

• Mi ricordo di chiamare = I remember to call
• Si ricordi di arrivare presto = Remember to arrive early

So di arrivare means to arrive after the verb remember.

This is a very common question.

In many contexts:

• ricordare qualcosa = to remember something
• ricordarsi di qualcosa / di fare qualcosa = to remember something / to remember to do something

Examples:

• Ricordo quel film = I remember that film
• Mi ricordo di quel film = I remember that film
• Mi ricordo di chiamarlo = I remember to call him

In everyday Italian, ricordare and ricordarsi often overlap, but ricordarsi di + infinitive is especially common for remember to do.

Arrivare focuses on reaching the destination: to arrive.

So arrivare presto means to arrive early.

You could sometimes use venire presto in other contexts, but that would mean to come early, with more emphasis on movement toward the speaker. Here, the important idea is getting there before the crowds, so arrivare is the most natural choice.

It means after eight o’clock.

Italian uses the feminine plural article with clock times:

• l’una = one o’clock
• le due = two o’clock
• le otto = eight o’clock

So:

• dopo le otto = after eight

If the context is clear, Italians often leave out ore.

Because when telling time, Italian normally uses the article:

• È l’una
• Sono le due
• dopo le otto
• alle nove

So le is part of the standard way of referring to the hour.

English learners often want to translate directly from after eight, but Italian prefers after the eight, in effect: dopo le otto.

Because gente is a singular collective noun in Italian. It means people in a collective sense, but grammatically it is singular.

So you say:

• c’è molta gente = there are a lot of people
• questa gente è rumorosa = these people are noisy

Not normally:

• molte genti in everyday Italian

That form exists in more literary or specialized uses, but not for ordinary conversation.

Because gente is grammatically singular feminine, so the adjective must agree with it:

• molta gente
• troppa gente
• poca gente

Even though the meaning is plural in English, the grammar in Italian is singular.

Yes, both are natural.

• c’è molta gente = very natural, common
• c’è tanta gente = also very common, a bit more conversational
• ci sono molte persone = also correct, slightly more literal as there are many people

So the original sentence is completely natural, but there are other good ways to express the same idea.

The comma separates an introductory topic phrase from the rest of the sentence.

So the structure is roughly:

• As for New Year’s, remember to arrive early...

This kind of comma is common when a phrase is moved to the front to set the context.

Without the comma, the sentence might still be understandable, but the comma makes the opening phrase feel more clearly like a scene-setting introduction.

Perché here means because.

So the sentence structure is:

• si ricordi di arrivare presto = remember to arrive early
• perché dopo le otto c’è molta gente = because after eight there are a lot of people

It introduces the reason for the advice.

Because it is a contraction of ci è.

In modern Italian, this is written:

• c’è = there is
• ci sono = there are

So:

• c’è molta gente = there are a lot of people / literally there is much crowd/people

The apostrophe shows that a vowel has dropped.

It is overall formal/polite, mainly because of si ricordi.

Everything else in the sentence is neutral and common, but that verb form clearly shows the speaker is addressing someone politely, perhaps:

• a customer
• a guest
• someone older
• someone not addressed on familiar terms

If you wanted the informal tu version, it would be:

• Per Capodanno, ricordati di arrivare presto, perché dopo le otto c’è molta gente.