Ana esqueceu seu casaco no sofá.

Esqueceu is the preterite form of esquecer (to forget).

Here it shows a completed past action: Ana forgot her coat at some specific moment in the past.

• esquecer = infinitive, to forget
• esqueceu = he/she/you(formal) forgot

So the sentence describes one finished event, not an ongoing or habitual action.

Because the subject is Ana, which is third person singular.

Portuguese verb forms change depending on the subject:

• eu esqueci = I forgot
• você/ele/ela esqueceu = you/he/she forgot
• eles/elas esqueceram = they forgot

Since Ana is one person, the verb must be esqueceu.

In Portuguese, proper names often appear without an article, especially in many neutral written contexts:

• Ana esqueceu seu casaco no sofá.

In some varieties of Brazilian Portuguese, people do use an article before names:

• A Ana esqueceu seu casaco no sofá.

Both can be natural, depending on region and style. For a learner, the version without the article is completely normal and easy to recognize.

Here seu means her in context, so seu casaco means her coat.

But this is important: seu/sua can also mean:

• your (formal, or referring to você)
• his
• her

So by itself, seu can be ambiguous. In this sentence, because the subject is Ana, most people will understand it as her coat.

Yes, it can be ambiguous.

Depending on context, seu casaco could mean:

• her coat
• his coat
• your coat

If you want to be extra clear in Brazilian Portuguese, you can say:

• o casaco dela = her coat
• o casaco dele = his coat
• o seu casaco or o casaco de você in some contexts for your coat
  (though de você is less elegant and more colloquial)

So a clearer version would be:

• Ana esqueceu o casaco dela no sofá.

Because casaco is a masculine noun.

In Portuguese, possessives agree with the thing possessed, not with the owner.

So:

• seu casaco = her/his/your coat
  because casaco is masculine
• sua bolsa = her/his/your purse/bag
  because bolsa is feminine

Even though Ana is female, the possessive matches casaco, not Ana.

Because em + o contracts to no.

So:

• em o sofá → no sofá
• em a cadeira → na cadeira
• em os carros → nos carros
• em as casas → nas casas

This contraction is required in normal Portuguese.

Great question. Portuguese often uses em where English uses in, on, or at, depending on context.

So:

• no sofá = on the sofa
• na mesa can mean on the table
• na escola = at school
• no carro = in the car

English and Portuguese do not always divide location prepositions in the same way. You usually learn them as part of natural usage.

Not in this sentence.

Esquecer can be used directly with an object:

• Ela esqueceu o casaco. = She forgot the coat.

But Portuguese also often uses esquecer de when followed by another verb or certain complements:

• Ela esqueceu de ligar. = She forgot to call.
• Esqueci de fazer isso. = I forgot to do that.

So in Ana esqueceu seu casaco no sofá, the direct object is seu casaco, and no preposition is needed before it.

It tells you where the coat was left/forgotten: on the sofa.

So the structure is:

• Ana = subject
• esqueceu = verb
• seu casaco = direct object
• no sofá = location

It does not mean that Ana was on the sofa when she forgot in any strongly emphasized way. The natural reading is that the coat ended up on the sofa.

In some contexts, yes, that is a natural English interpretation.

Portuguese esquecer literally means to forget, but in sentences like this, English often says left:

• Ana esqueceu seu casaco no sofá.
• Natural English: Ana left her coat on the sofa.

Why? Because in English, forgot her coat on the sofa sounds less natural than left her coat on the sofa, even though the idea is that she forgot it there.

So the Portuguese focuses on the act of forgetting; English often prefers the result: she left it there.

Yes, but the meaning changes a little.

• Ana esqueceu seu casaco no sofá = Ana forgot her coat on the sofa / left it there by mistake
• Ana deixou seu casaco no sofá = Ana left her coat on the sofa

Deixou does not necessarily mean she forgot it. It could have been intentional.
Esqueceu clearly suggests it was accidental or unintentional.

Yes. In Brazilian Portuguese, both are possible:

• seu casaco
• o seu casaco

Both can mean his/her/your coat.

In everyday Brazilian Portuguese, dropping the article before a possessive is very common, especially in simpler sentences like this one. Adding the article can sound a bit more explicit or natural in some regions and contexts.

So all of these are possible:

• Ana esqueceu seu casaco no sofá.
• Ana esqueceu o seu casaco no sofá.
• Ana esqueceu o casaco dela no sofá.

Yes, but the original order is the most neutral:

• Ana esqueceu seu casaco no sofá.

Other orders are possible for emphasis, for example:

• No sofá, Ana esqueceu seu casaco.
  This emphasizes the location.
• Seu casaco, Ana esqueceu no sofá.
  This sounds more marked and is less neutral.

For learners, the original order is the best default: subject + verb + object + location

Sofá is pronounced roughly so-FAH, with stress on the last syllable.

The accent mark on á shows that the stress falls there:

• so-fá

Without the accent, Portuguese spelling rules would suggest a different stress pattern or make the word look incorrect. So the accent helps mark the correct pronunciation.

In Brazilian Portuguese, esqueceu is pronounced approximately like:

• es-ke-SEW

The stress is on the last syllable:

• es-que-CEU

A few pronunciation notes:

• qu in esqueceu sounds like a hard k
• the ending -eu often sounds something like ew in English, though not exactly the same

So a helpful rough guide is es-ke-SEW.

Yes, it is completely natural.

It is a simple, everyday sentence with very common vocabulary and structure:

• Ana = proper name
• esqueceu = common past-tense verb
• seu casaco = ordinary possessive phrase
• no sofá = common location phrase

A Brazilian speaker would understand it immediately.