A caixa me deu o recibo.

Caixa can mean different things depending on context:

• box
• cash register / checkout
• cashier

In A caixa me deu o recibo, the context makes a caixa mean the female cashier.

So this sentence is understood as talking about a person, not a box.

Here, a caixa is feminine, so it normally refers to a female cashier.

A few useful points:

• a caixa = the female cashier
• o caixa = the male cashier, or sometimes the checkout/cash register, depending on context

So the article changes with the meaning and/or the person’s gender.

Me means to me here.

With the verb dar (to give), Portuguese often uses an indirect object pronoun:

• A caixa me deu o recibo.
• literally: The cashier gave me the receipt
• more literally: The cashier gave the receipt to me

So:

• me = to me
• o recibo = the thing being given

It is an indirect object.

In dar sentences, there are usually two objects:

• the thing being given = direct object
• the person receiving it = indirect object

So in this sentence:

• me = indirect object = to me
• o recibo = direct object = the receipt

In Brazilian Portuguese, putting me before the verb is very common and natural:

• A caixa me deu o recibo.

You may also see deu-me, but in Brazil that sounds:

• more formal
• more literary
• sometimes more European Portuguese in style

So for everyday Brazilian Portuguese, me deu is the version learners should get used to hearing most often.

Deu is the preterite (simple past) of dar.

The infinitive is:

• dar = to give

The form deu means:

• gave

This tense is used for a completed action in the past. The cashier gave the receipt, and that action is finished.

Because deu describes a single completed event.

• deu = gave, one completed action
• dava = was giving / used to give / would give, depending on context

Here the idea is simple: the cashier handed over the receipt. That is a completed action, so deu fits best.

Yes, that is possible, but it is less compact and often less natural in a sentence like this.

Compare:

• A caixa me deu o recibo. = very natural
• A caixa deu o recibo para mim. = possible, but heavier

In Portuguese, when the recipient is a pronoun like me, te, lhe, etc., using the clitic pronoun is very common.

So me deu is usually the best everyday choice here.

O recibo means the receipt, a specific receipt.

That makes sense because in a real situation, both speaker and listener usually know which receipt is being talked about: the one from that purchase or transaction.

Compare:

• o recibo = the receipt, a specific one
• um recibo = a receipt, any one / not previously identified

It is a correct word, but in Brazil the most natural word can depend on the situation.

You may also hear:

• nota fiscal = official sales receipt / invoice
• cupom fiscal = printed store receipt
• comprovante = proof of payment / receipt slip

Recibo is absolutely understandable and correct, especially in more general contexts or when someone acknowledges receiving payment. But in many store situations, Brazilians might say nota fiscal or comprovante instead.

The structure is:

• A caixa = subject
• me = indirect object pronoun
• deu = verb
• o recibo = direct object

So the pattern is roughly:

• Subject + pronoun + verb + object

In very literal terms:

• The cashier + to me + gave + the receipt

But in natural English, of course, we say:

• The cashier gave me the receipt.

In Brazilian Portuguese, deu is usually pronounced as one syllable, not two fully separate syllables.

A rough English approximation is something like:

• deh-oo compressed into one quick syllable
• or almost like dayw, depending on accent

It is not usually pronounced slowly as de-u in normal speech.

Not if you want to say gave me the receipt specifically.

Compare:

• A caixa me deu o recibo. = The cashier gave me the receipt.
• A caixa deu o recibo. = The cashier gave the receipt.

Without me, the sentence no longer says who received it. So me is necessary if I am the recipient.