O trinco da janela está solto, e a Maria pediu ao pai dela que o apertasse.

Trinco is the part of a door or window that fastens or secures it shut — often a latch, catch, or bolt, depending on the exact type.

In this sentence, o trinco da janela is the window’s fastening mechanism.

Because da is the normal contraction of de + a.

• de = of
• a = the
• da = of the

So:

• o trinco da janela = the latch of the window

This kind of contraction is extremely common in Portuguese:

• de + o = do
• de + a = da
• a + o = ao
• a + a = à

Portuguese usually uses estar for a temporary state or condition, and ser for something more permanent or defining.

Here, solto means loose, so está solto means the latch is currently loose.

• está solto = it is loose right now / it has come loose
• é solto would sound more like a general characteristic, which does not fit well here

So está is the natural choice.

In European Portuguese, it is very common to use the definite article before people’s names in everyday speech.

So:

• a Maria
• o João
• a Ana

This does not mean the Maria in English. It is just a normal Portuguese feature, especially in Portugal.

You may sometimes see names without the article, especially in writing or in more formal contexts, but in spoken European Portuguese the article is very common.

The verb pedir often works with this structure:

• pedir a alguém que... = to ask someone to...

So:

• pediu ao pai dela = she asked her father

Here, ao is a contraction of a + o:

• a o pai → ao pai

So the structure is:

• pediu = asked
• ao pai dela = to her father
• que o apertasse = that he tighten it

This is a very common pattern in Portuguese.

Because dela is clearer.

Both can refer to possession, but seu/sua can sometimes be ambiguous in Portuguese. It might mean:

• his
• her
• your

So ao pai dela clearly means to her father, referring to Maria.

In European Portuguese, speakers often use dele/dela to avoid confusion.

Compare:

• ao seu pai = to her father / his father / your father, depending on context
• ao pai dela = clearly Maria’s father

Because after pedir in a past sentence, Portuguese commonly uses que + subjunctive.

Here:

• pediu ... que ... apertasse

The form apertasse is the imperfect subjunctive of apertar.

This happens because the sentence reports a request made in the past:

• A Maria pediu ... que o apertasse.
• Maria asked ... that he tighten it.

A useful comparison:

• A Maria pede que o aperte. = present-time request
• A Maria pediu que o apertasse. = past-time request

So the tense and mood are being controlled by pediu.

The o is a direct object pronoun meaning it.

It refers back to o trinco.

So:

• o trinco = the latch
• que o apertasse = that he tighten it

Because trinco is masculine singular, the pronoun is o.

If the noun were feminine, you would use a instead.

Because in European Portuguese, certain words trigger proclisis, which means the object pronoun goes before the verb.

The word que is one of those triggers.

So:

• que o apertasse is correct

Not:

• que apertasse-o

This is an important pattern to notice in Portuguese. Pronoun placement is not random; it depends on the structure.

In this sentence, que pulls the pronoun in front of the verb.

Apertar has several meanings depending on context, including:

• to tighten
• to press
• to squeeze

Here, because the latch is solto (loose), apertar means something like:

• tighten
• fasten more firmly
• possibly secure

So it is not about physically pressing it once; it suggests making it properly tight again.

Yes. A common alternative would be:

• O trinco da janela está solto, e a Maria pediu ao pai dela para o apertar.

This uses:

• pedir a alguém para + infinitive

instead of:

• pedir a alguém que + subjunctive

Both are natural. The version with que o apertasse is perfectly correct and very common, but learners should know that para + infinitive is also widely used.

Not always.

If the context already makes it obvious that the father is Maria’s father, Portuguese could simply say:

• A Maria pediu ao pai que o apertasse.

But dela makes the relationship explicit and removes any doubt.

So:

• ao pai = possibly enough from context
• ao pai dela = clearer and more explicit

Writers and speakers often include dela when they want to avoid ambiguity.