Después de pasar la mopa, mi hermano dejó la bayeta junto al fregadero para que se secara.

Because after the preposition de, Spanish normally uses an infinitive, not a conjugated verb.

So:

• después de pasar la mopa = after mopping / after using the mop

This is especially common when the subject is the same as the main clause, or when Spanish simply presents the action in a general way.

If you wanted a full clause with a conjugated verb, you would normally use después de que:

• Después de que pasó la mopa... = after he mopped...

So the pattern here is:

• después de + infinitive
• después de que + finite verb

In Spanish, pasar is very commonly used with cleaning tools to mean to run / use / go over with that tool.

So:

• pasar la mopa = to mop / to run the mop over the floor
• pasar la aspiradora = to vacuum
• pasar un trapo = to wipe with a cloth

This is a very natural collocation in Spanish, even though English usually chooses a more specific verb like mop or wipe.

In Spain, mopa and fregona are not always the same thing.

Usually:

• mopa = a mop used for dusting or lightly cleaning the floor, often a flat mop
• fregona = the more traditional wet mop used for washing the floor

So pasar la mopa often suggests going over the floor with a mop, not necessarily doing a full wet scrub.

Usage can vary a bit by region and context, but this is the usual distinction in Spain.

A bayeta is a cleaning cloth, especially the kind used in kitchens or for wiping surfaces.

For an English speaker, nearby words are:

• bayeta = cleaning cloth
• trapo = rag / cloth, more general
• toalla = towel

In Spain, bayeta is a very common household word.

Because it describes a completed action in the past:

• he left the cloth next to the sink

The sentence narrates a sequence of finished actions:

1. he passed the mop
2. he left the cloth by the sink

That makes the preterite a natural choice:

• dejó

If the sentence were describing background or habitual action, the imperfect might be used instead, but here it is a specific completed event.

Because junto a means next to / beside, and a + el contracts to al.

So:

• junto a el fregadero → junto al fregadero

This contraction happens whenever a is followed by el:

• voy al mercado
• junto al fregadero

But it does not happen with la:

• junto a la puerta

Also, junto a is the normal expression here; Spanish does not say junto de in this meaning.

In Spain, fregadero usually refers to the kitchen sink.

Compare:

• fregadero = kitchen sink
• lavabo = bathroom sink / washbasin

Since the sentence talks about cleaning items like a mop and a cloth, fregadero fits very naturally.

Because para que introduces a purpose clause, and after para que, Spanish uses the subjunctive.

So:

• para que se secara = so that it would dry / so it could dry

This structure is very common:

• Lo dejé allí para que se enfriara.
• Abrí la ventana para que entrara aire.

Why not para secarse? Because secarse would not sound as natural here for the intended meaning. La bayeta is not actively doing the action in the same way a person would. Spanish naturally expresses the idea as:

• he left it there so that it would dry

So para que + imperfect subjunctive is the normal choice.

Because it depends on para que, and the main verb is in the past.

Spanish often follows this sequence:

• main verb in the present → present subjunctive
• main verb in the past → imperfect subjunctive

So:

• La dejo allí para que se seque. = I leave it there so that it dries
• La dejó allí para que se secara. = He left it there so that it would dry

That is why secara appears here instead of seque.

Here, secarse means to dry / to become dry.

Compare:

• secar = to dry something
  
  • Secó la bayeta. = He dried the cloth.
• secarse = to dry, to get dry
  
  • La bayeta se secó. = The cloth dried.

So in para que se secara, the cloth is not being dried directly by someone; it is being left somewhere so that it can dry itself / become dry.

This is a very common Spanish pattern with change-of-state verbs:

• romper / romperse
• abrir / abrirse
• secar / secarse

Spanish uses articles more often than English does.

With everyday objects, Spanish often prefers the definite article where English might use:

• no article
• a possessive
• a more general noun phrase

So Spanish naturally says:

• pasar la mopa
• dejó la bayeta junto al fregadero

Even though English might say:

• after mopping
• he left the cloth by the sink

This is normal Spanish style, not something unusual about this sentence.

It is an introductory time expression. Spanish often places this kind of phrase first to set the scene:

• Después de pasar la mopa, mi hermano dejó la bayeta...

This is similar to English:

• After mopping, my brother left the cloth...

You could also place it later:

• Mi hermano dejó la bayeta junto al fregadero después de pasar la mopa.

Both are grammatical, but the original version sounds slightly more narrative and organized: first the earlier action, then the next one.

Yes. Both are valid imperfect subjunctive forms of secarse:

• se secara
• se secase

In modern Spanish, especially in everyday use, the -ra form is much more common:

• para que se secara

The -se form is correct but can sound more formal, literary, or less common in conversation, depending on the speaker and region.