Marta parte per il mare a luglio con sua sorella.

Parte comes from partire, which means to leave, to depart, or to set off.

So:

• Marta parte = Marta leaves / sets off
• Marta va = Marta goes

Both can sometimes work in similar situations, but they focus on slightly different things:

• partire emphasizes the moment of departure
• andare emphasizes going to a destination

In this sentence, parte per il mare suggests Marta sets off for the seaside.

Also, parte is the third person singular of partire in the present tense, matching Marta.

Italian often uses the present tense to talk about a planned or expected future action, especially when there is a clear time expression.

Here, a luglio makes the time clear, so parte can naturally refer to the future:

• Marta parte a luglio = Marta is leaving in July / Marta leaves in July

This is very common in Italian, just like in English when you say:

• She leaves in July
• We’re going next week

Italian could also use a future tense in some contexts, but the present is very normal here.

Literally, per il mare means for the sea, but in natural usage it means for the seaside / toward the sea.

With verbs like partire, per often introduces the destination:

• partire per Roma = to leave for Rome
• partire per l’Italia = to leave for Italy
• partire per il mare = to leave for the seaside

So per works well because partire per is a common pattern meaning to depart for a place.

In this sentence, il mare does not just mean the water itself. In Italian, andare al mare or partire per il mare often means to go to the seaside / to the coast, especially for a holiday.

In Italian, il mare is often used where English would say the seaside, the coast, or sometimes even the beach in a general holiday sense.

So:

• andare al mare usually means to go to the seaside
• it does not necessarily mean to go into the water

If you specifically want the beach, that is la spiaggia.

Compare:

• Vado al mare = I’m going to the seaside
• Vado in spiaggia or vado sulla spiaggia = I’m going to the beach

So il mare is idiomatic and very common in Italian.

With months, Italian normally uses a:

• a luglio = in July
• a giugno = in June
• a dicembre = in December

So a luglio is the standard everyday choice.

You may sometimes see in luglio, but a luglio is much more common in modern usage.

In Italian, singular family members usually take a possessive without the article.

So you usually say:

• mia madre
• tuo fratello
• sua sorella
• nostro padre

That is why the sentence has con sua sorella.

But there are important exceptions. The article is often used when:

1. the family noun is plural

   • le sue sorelle

2. the family noun is modified

   • la sua sorella maggiore

3. you use affectionate or altered forms in many contexts

   • la mia sorellina

So sua sorella is correct because it is a singular, unmodified family member.

Sua here is understood as her, referring to Marta, so con sua sorella means with her sister.

But grammatically, the possessive adjective agrees with the thing possessed, not with the owner.

Here:

• sorella is singular feminine
• so the possessive is sua

Compare:

• suo fratello = her/his brother
• sua sorella = her/his sister
• suoi fratelli = her/his brothers
• sue sorelle = her/his sisters

So sua is feminine singular because sorella is feminine singular.

Yes. Suo / sua / suoi / sue can mean his or her. Italian does not distinguish between them in the possessive form.

So:

• sua sorella can mean his sister or her sister

You understand which one is meant from context.

In this sentence, since the subject is Marta, it is naturally understood as her sister.

No. Italian word order is fairly flexible, although this sentence uses a very normal neutral order:

• Marta = subject
• parte = verb
• per il mare = destination
• a luglio = time
• con sua sorella = accompaniment

You could move some parts around without changing the basic meaning, for example:

• A luglio Marta parte per il mare con sua sorella.
• Marta parte a luglio per il mare con sua sorella.

These variations may slightly change emphasis, but they are all natural.

It tells you who Marta is traveling with, so it goes with the action of leaving.

• con sua sorella = with her sister

In other words, Marta is not just being described as someone who has a sister. The phrase shows that her sister is accompanying her on the trip.

Then you would use the plural:

• Marta parte per il mare a luglio con le sue sorelle.

Notice the changes:

• sorella → sorelle
• sua → sue
• now the article appears: le sue sorelle

That article is needed because plural family members normally do take the article.