Minha filha está no banco de trás.

Because filha is a feminine singular noun, so the possessive has to agree with it.

• minha = my, for feminine singular nouns
• meu = my, for masculine singular nouns

So:

• minha filha = my daughter
• meu filho = my son

In Brazilian Portuguese, possessives can appear with or without the definite article.

So both of these are possible:

• Minha filha está no banco de trás.
• A minha filha está no banco de trás.

In everyday Brazilian Portuguese, leaving the article out is very common, especially with family words like mãe, pai, filho, and filha.

Because Portuguese normally uses estar for physical location.

• Minha filha está no banco de trás. = My daughter is in the back seat.

Using ser here would sound wrong. In Portuguese, ser is generally not used to say where someone or something is located.

No is a contraction of:

• em
  • o = no

It means in/on/at the with a masculine singular noun.

Since banco is masculine, em o banco becomes no banco.

Compare:

• no carro = in the car
• na cadeira = in/on the chair

Here, na is em + a because cadeira is feminine.

Yes. Banco has several meanings in Portuguese, including:

• bank
• bench
• seat

In a car context, banco usually means seat. So banco de trás means back seat or rear seat, not a financial institution.

De trás means from the back, in the back, or rear, depending on context.

In banco de trás, it describes which seat we mean: the one at the back.

So:

• banco de trás = back seat / rear seat

It is a very natural way to refer to the rear seat of a car.

Because de trás is being used to describe the noun banco.

• banco de trás = back seat

By contrast, atrás is usually more like behind or in back as an adverb or location word.

For example:

• Minha filha está atrás. = My daughter is in back / behind.

That sentence is possible, but it does not specify the seat as clearly. No banco de trás is more precise and more natural for in the back seat.

Because in Portuguese, o banco de trás often refers to the whole rear seating area as one unit.

This is similar to English, where the back seat can also mean the whole rear seat area, not just one sitting spot.

If you wanted to talk about separate rear seats, you could say:

• os bancos de trás = the back seats

But no banco de trás is the normal expression for in the back seat.

Yes, absolutely. That is also correct.

Both are natural:

• Minha filha está no banco de trás.
• A minha filha está no banco de trás.

In Brazilian Portuguese, the version without the article is often very common in everyday speech, but the version with the article is also widely used.

These two words contain sounds that can be tricky for English speakers.

• minha is roughly MEEN-ya
• filha is roughly FEE-lya

A couple of important points:

• nh in minha sounds like ny in canyon
• lh in filha sounds similar to the lli sound many speakers use in million

So do not pronounce:

• minha like mina
• filha like fill-ha

The special consonants matter a lot in Portuguese pronunciation.