A entrega não chegou no horário porque a funcionária deixou um envelope no prédio errado.

In this sentence, porque means because, so it is written as one word:

A entrega não chegou no horário porque a funcionária deixou um envelope no prédio errado.
= The delivery didn’t arrive on time because the employee left an envelope in the wrong building.

A quick rule:

• porque = because
• por que = why / for what reason

So if you could replace it with because, porque is correct.

Chegou is the preterite form of chegar and means arrived.

• chegar = to arrive
• não chegou = did not arrive / didn’t arrive

The preterite is used because the sentence describes a completed past event: the delivery failed to arrive on time.

So:

• A entrega não chegou = The delivery didn’t arrive

Here, entrega means delivery.

It can refer to:

• the act of delivering something
• the item/order being delivered
• a delivery service or delivery run, depending on context

In this sentence, a entrega most naturally means the delivery—the expected package/document/item that was supposed to arrive.

No is a contraction of em + o:

• em = in / at / on
• o horário = the scheduled time / the proper time

So:

• em o horário → no horário

Here, no horário means on time, at the scheduled time, or at the expected time.

It is masculine because horário is a masculine noun:

• o horário
• therefore no horário

Usually, yes. In this sentence, não chegou no horário is naturally understood as didn’t arrive on time.

But no horário can also carry the idea of at the scheduled time or at the correct hour, depending on context.

Related expressions:

• no horário = on time / at the scheduled time
• na hora = at the time / right then / on time in some contexts
• a tempo = in time, before it was too late

So no horário is the best fit here because it focuses on the expected or planned arrival time.

Funcionária means female employee / staff member / worker.

It is feminine because of the ending and because it refers to a woman:

• o funcionário = male employee
• a funcionária = female employee

So a funcionária deixou... means the employee left..., specifically a female employee.

Here, deixou means left in the sense of placed / dropped off / left behind.

• deixar can mean to leave, to put, to leave behind, and sometimes to let / allow
• In this sentence, the meaning is clearly left: she left an envelope in the wrong building

So:

• deixou um envelope no prédio errado
  = left an envelope in the wrong building

It does not mean allowed here.

Um envelope means an envelope.

Portuguese is using the indefinite article because the envelope is being introduced as a piece of information, not as something already specifically identified for the listener.

• um envelope = an envelope
• o envelope = the envelope

If the speaker and listener already knew exactly which envelope was being discussed, o envelope would be more likely. But in this sentence, um envelope sounds natural.

Again, no is the contraction of em + o:

• o prédio = the building
• em o prédio → no prédio

So:

• no prédio = in the building / at the building

With errado, it becomes:

• no prédio errado = in the wrong building

This is the place where the envelope was left.

In Portuguese, adjectives often come after the noun.

So:

• prédio errado = wrong building
• envelope grande = big envelope
• carro novo = new car

That is the normal word order. English usually puts adjectives before the noun, but Portuguese often places them after.

Also, errado agrees with prédio, which is masculine singular:

• prédio = masculine singular
• errado = masculine singular

If the noun were feminine, it would change:

• a sala errada = the wrong room

Portuguese uses definite articles more often than English.

So it is very normal to say:

• a entrega
• a funcionária

Even where English might say just delivery or the employee depending on context, Portuguese often prefers the article.

In this sentence, the articles make both nouns sound like specific, identifiable things in the situation:

• a entrega = the delivery
• a funcionária = the employee

This is one of the most common differences English speakers notice in Portuguese.

Sometimes, but it changes the feel a little.

• no horário = on schedule / at the expected time
• na hora = at the time / right then / on time in some situations

In this sentence, no horário is better because the idea is that the delivery did not arrive at the scheduled time.

So:

• A entrega não chegou no horário = very natural
• A entrega não chegou na hora = possible in some contexts, but less precise here

The sentence breaks down like this:

• A entrega = subject
• não chegou no horário = main action
• porque = introduces the reason
• a funcionária deixou um envelope no prédio errado = explanation/reason

So the full structure is:

[Main statement] + [because] + [reason]

More literally:

• The delivery did not arrive on time because the employee left an envelope in the wrong building.

This is a very common and useful Portuguese pattern for giving a reason:

• X aconteceu porque Y
• X happened because Y