El edredón puede encogerse en la lavadora.

El is the masculine singular definite article, meaning the.

• el edredón = the comforter / duvet
• Spanish nouns usually need an article more often than English nouns do.

Here, edredón is a masculine noun, so it takes el, not la.

Not exactly. Edredón usually refers to a comforter, duvet, or quilted bed covering, not just any blanket.

A few useful distinctions:

• edredón = comforter / duvet
• manta = blanket
• sábana = sheet

So if you are talking about the thick padded bed covering, edredón is the right word.

Because the subject is singular: el edredón.

• el edredón puede = the comforter can
• los edredones pueden = the comforters can

The verb poder has to agree with the subject:

• yo puedo
• tú puedes
• él/ella/usted puede
• ellos/ellas/ustedes pueden

So puede matches el edredón.

In this sentence, puede means something like can or may possibly.

So El edredón puede encogerse en la lavadora means the comforter is capable of shrinking / may shrink in the washing machine.

Spanish poder often covers ideas that in English can be translated as:

• can
• may
• might

The best translation depends on context.

Because encogerse is the common way to say to shrink when something shrinks itself, especially with clothes or fabric.

• encoger can mean to shrink something or to make something smaller
• encogerse means to shrink / to become shrunken

Examples:

• La lavadora encogió la camisa.
  The washing machine shrank the shirt.
  Here, something causes the shrinking.

• La camisa se encogió.
  The shirt shrank.
  Here, the shirt itself underwent the change.

In your sentence, the comforter is the thing that may shrink, so encogerse is natural.

Grammatically, yes, this is the reflexive form, but in meaning it is often better understood as a change of state rather than a literal reflexive action.

So encogerse does not mean the comforter is deliberately shrinking itself. It means it becomes shrunken.

This is very common in Spanish with verbs that describe changes:

• romper = to break something

• romperse = to break / become broken

• quemar = to burn something

• quemarse = to burn / get burned

• encoger = to shrink something
• encogerse = to shrink

Because after a conjugated verb like puede, Spanish often uses an infinitive, and reflexive pronouns can be attached to the infinitive.

So:

• puede encogerse
• literally: can shrink itself / can shrink

This is normal Spanish structure.

You could compare it with other examples:

• puede lavarse = can wash himself/herself
• va a dormirse = is going to fall asleep
• quiere sentarse = wants to sit down

With an infinitive, attaching the pronoun to the end is standard.

Yes, but it changes the structure and emphasis.

• El edredón puede encogerse
  = The comforter can shrink.

• El edredón se puede encoger
  = The comforter can shrink / The comforter can end up shrinking.

Both are natural, and in many contexts the meaning is very similar.

A small difference:

• puede encogerse sounds slightly more direct and compact.
• se puede encoger keeps the reflexive pronoun with the conjugated part of the verb phrase.

Both are correct.

En la lavadora means in the washing machine or in the washer.

Spanish uses en for location or where something happens.

• en la lavadora = in the washing machine
• en el horno = in the oven
• en el coche = in the car

Here it tells you the situation in which the shrinking happens: while it is in the washing machine.

Yes. Lavadora is widely understood across Latin America, but some regions also use other words, especially for washing machine.

For example, in some places people may say:

• lavadora
• lavarropas

Both can mean washing machine, depending on the country.

So en la lavadora is standard and widely understood.

The accent mark shows where the stress goes: e-dre-DÓN.

Without the accent, Spanish stress rules would suggest a different pronunciation. The written accent tells you that the final syllable is stressed.

So pronounce it roughly as:

• ed-re-DON

That final -dón is the stressed part.

Yes, somewhat. The most neutral order is:

• El edredón puede encogerse en la lavadora.

But Spanish can move things around for emphasis:

• En la lavadora, el edredón puede encogerse.
• El edredón, en la lavadora, puede encogerse.

These are possible, but the original sentence is the most natural neutral version for everyday use.

A few natural alternatives are:

• El edredón puede encogerse en la lavadora.
• Este edredón puede encogerse al lavarlo a máquina.
• Puede encogerse en la lavadora.
• Se puede encoger en la lavadora.

If you want a stronger warning, you might also see:

• No lavar a máquina; puede encogerse.
• Puede encogerse si se lava en lavadora.

These sound more like care-label language.