La pelusa queda en el filtro de pelusa.

Here queda comes from the verb quedar. In this sentence, it means something like:

• stays
• remains
• ends up

So La pelusa queda en el filtro de pelusa means the lint stays/remains in the lint filter.

A useful thing to know is that quedar often has this idea of where something is left after a process.

Examples:

• El agua queda en el vaso. = The water remains in the glass.
• La comida queda en la olla. = The food stays in the pot.

Because the two instances do different jobs:

• The first pelusa is the thing being talked about: the lint
• The second pelusa is part of the noun phrase filtro de pelusa, which means lint filter

So the structure is:

• La pelusa = the lint
• queda = stays / remains
• en el filtro de pelusa = in the lint filter

This repetition sounds normal in Spanish, even if it feels repetitive in English.

In filtro de pelusa, de connects the two nouns and shows what kind of filter it is.

So filtro de pelusa literally looks like:

• filter of lint

But in natural English, we say:

• lint filter

Spanish often uses noun + de + noun where English often uses two nouns together.

More examples:

• taza de café = coffee cup
• jugo de naranja = orange juice
• cepillo de dientes = toothbrush

So filtro de pelusa is a very normal Spanish structure.

Spanish uses definite articles more often than English.

Here:

• La pelusa = the lint
• el filtro de pelusa = the lint filter

Even when English might sound more general, Spanish often still uses el / la / los / las.

So Spanish is not necessarily emphasizing this specific lint. It can simply be talking about lint in general in a normal, definite way.

Because pelusa is usually treated as a mass noun here, like dust, hair, or lint in English.

You normally talk about it as a substance rather than as individual pieces.

So:

• la pelusa = lint

Not usually:

• las pelusas unless you mean separate little bits or clumps of fuzz/lint

For example:

• Hay pelusa en la ropa. = There is lint on the clothes.
• Quité unas pelusas de la camisa. = I removed some little bits of lint from the shirt.

Because the subject is la pelusa, which is singular.

Even though lint is made up of many tiny fibers, the noun pelusa is grammatically singular here.

So:

• La pelusa queda... = singular subject + singular verb

If the subject were plural, then the verb would change:

• Las pelusas quedan... = The bits of lint remain...

Pelusa can mean lint, fuzz, fluff, or downy fibers, depending on context.

In a laundry or dryer context, pelusa is very naturally understood as lint.

In other contexts, it can also refer to:

• fuzz on fabric
• soft fluff
• fine hair-like fibers
• even peach fuzz in some situations

So the exact English translation depends on context, but in this sentence lint is the best choice.

En is the normal preposition for location in Spanish, and it often covers both in and on, depending on context.

Here, en el filtro de pelusa means in the lint filter.

Spanish does not always separate in and on as strictly as English does. En is very common for both kinds of location.

Examples:

• en la caja = in the box
• en la mesa = on the table
• en el filtro = in the filter

So en is exactly what you would expect here.

Yes, La pelusa se queda en el filtro de pelusa can also work, and it may sound more natural to some speakers in everyday speech.

The difference is subtle:

• queda can sound a little more descriptive or neutral: it remains / it ends up
• se queda often feels a bit more like it stays behind

In many contexts, both are possible.
For example:

• La pelusa queda en el filtro.
• La pelusa se queda en el filtro.

Both are understandable and natural.

Yes, it is understandable and natural enough, especially in an explanatory context.

That said, many speakers might also say things like:

• La pelusa se queda en el filtro.
• La pelusa queda atrapada en el filtro.
• La pelusa se acumula en el filtro.

These versions add slightly different shades of meaning:

• se queda = stays
• queda atrapada = gets trapped
• se acumula = builds up / accumulates

Also, the exact term for lint filter may vary a little by region or by appliance, but filtro de pelusa is easy to understand.

You could map it that way to understand the grammar, but it is not natural English.

A word-for-word breakdown is:

• La = the
• pelusa = lint
• queda = stays / remains
• en = in
• el = the
• filtro de pelusa = lint filter

Natural English would be:

• The lint stays in the lint filter.
• Lint remains in the lint filter.

So the Spanish structure is normal, but the most natural English translation is not fully word-for-word.