O Pedro corta o melão às rodelas para o lanche.

In European Portuguese, it is very common to use the definite article before a person's first name: o Pedro, a Maria, o João.

So o Pedro is a normal, natural way to say Pedro in everyday Portuguese from Portugal. It does not sound as strange as the Pedro would in English.

A few notes:

• It is especially common in speech and informal/neutral writing.
• You normally do not use the article when speaking directly to the person: Pedro, anda cá.
• In very formal styles, names may appear without the article.

Here, o melão means the melon: a specific melon that Pedro is cutting.

Portuguese often uses articles more than English does. In this sentence, the speaker is not talking about melon in general as a food; they mean a particular melon.

So:

• o melão = the melon
• melão by itself can appear in dictionary style, lists, labels, or more general statements depending on the context

Às rodelas means into round slices.

The noun rodela means a round slice, disk, or ring-shaped piece. It is often used for foods that can be cut crosswise, such as:

• cucumber
• onion
• sausage
• lemon
• carrot

So in this sentence, the melon is being cut into round pieces/slices, not into cubes or random chunks.

Às is a contraction of:

• a
  • as = às

Here:

• as is the feminine plural article, matching rodelas
• the grave accent in às shows that a contraction has happened

So às rodelas is literally built with a preposition plus the feminine plural article.

This pattern is common in expressions about how something is prepared:

• aos cubos = into cubes
• às tiras = into strips
• à mão = by hand

Yes. Cortar em rodelas is also correct and natural.

In Portugal, cortar às rodelas is very common and sounds very idiomatic in cooking or food-preparation contexts. Em rodelas is also perfectly understandable and natural.

So:

• cortar às rodelas = very common
• cortar em rodelas = also correct

The difference is small, and in many situations they mean essentially the same thing.

The simple present in Portuguese can do several jobs, just like in English. Depending on context, corta can mean:

• a habitual action: Pedro cuts the melon into slices
• a general description: Pedro cuts the melon into slices for snack time
• a present-time narrative style: Pedro cuts the melon...

If you want to make it very clear that the action is happening right now, European Portuguese usually prefers:

• O Pedro está a cortar o melão às rodelas.

So:

• corta = simple present
• está a cortar = is cutting, right now

No. Lanche is not lunch.

In Portugal, lanche usually means a snack or light meal, often in the afternoon.

Compare:

• pequeno-almoço = breakfast
• almoço = lunch
• lanche = snack / light meal
• jantar = dinner

So para o lanche means something like for the snack or for snack time, not for lunch.

Here, para expresses purpose or intended use.

So para o lanche means:

• for the snack
• to be eaten at snack time

It tells you why Pedro is cutting the melon.

Portuguese often uses an article with meals or eating occasions in expressions like this, so o lanche is normal here.

Yes, but the original order is very natural and clear.

Original:

• O Pedro corta o melão às rodelas para o lanche.

Possible alternatives:

• Para o lanche, o Pedro corta o melão às rodelas.
• O Pedro corta, para o lanche, o melão às rodelas.
  This is possible, but less neutral.

The original sentence works well because:

• o melão stays close to corta
• às rodelas stays close to the action it describes
• para o lanche comes naturally at the end as the purpose

Yes, if the subject is already clear from the context.

Portuguese often leaves out the subject when the verb ending already shows who the subject is. So you could say:

• Corta o melão às rodelas para o lanche.

That can mean:

• He cuts the melon into slices for the snack
• She cuts the melon into slices for the snack
• or even an instruction, depending on context

Including O Pedro makes the subject explicit and removes ambiguity.

These words all describe pieces of food, but not the same kind of pieces.

• rodelas = round slices
  Example: cucumber, onion, carrot, sausage

• fatias = slices, usually flatter or broader, not necessarily round
  Example: bread, ham, cheese, cake

• pedaços = pieces/chunks
  Example: melon cut into chunks

So with melon:

• às rodelas = in round slices
• em fatias = in slices/wedges
• aos pedaços = in pieces/chunks

The sentence specifically chooses às rodelas because it focuses on the melon being cut into round slices.