A missão terminou à noite.

Because missão is a feminine singular noun, and Portuguese often uses the definite article where English might not.

• a = the for feminine singular nouns
• missão = mission

So A missão literally means The mission.

In Portuguese, it is very natural to say A missão terminou, whereas in English you might sometimes prefer just Mission accomplished or The mission ended, depending on context.

Nouns in Portuguese have grammatical gender, and missão is a feminine noun.

That is why it takes:

• a in the singular: a missão
• as in the plural: as missões

This grammatical gender does not necessarily have anything to do with biological sex. It is simply a property of the noun that affects articles, adjectives, and some other words.

Terminou is the pretérito perfeito do indicativo in Portuguese, usually translated as the simple past in English.

It comes from the verb terminar = to finish / to end.

Conjugation:

• eu terminei = I finished
• tu terminaste = you finished
• ele/ela/você terminou = he/she/you finished

So A missão terminou means The mission ended or The mission finished.

Because terminou describes a completed event: the mission ended.

• terminou = ended / finished as a completed action
• terminava = was ending / used to end / would end, depending on context

So:

• A missão terminou à noite = The mission ended at night.
• A missão terminava à noite could mean something like The mission used to end at night or The mission was ending at night, which is a different idea.

À noite means at night or sometimes in the evening / at night, depending on context.

It is a time expression. In this sentence, it tells us when the mission ended.

Common time expressions:

• de manhã = in the morning
• à tarde = in the afternoon
• à noite = at night / in the evening

In European Portuguese, à noite is very common for this kind of general time reference.

The à is a contraction of:

• a = to / at
• a = the (feminine singular article)

So:

• a + a = à

In à noite, this contraction has become the standard expression.

The accent here is a grave accent and shows contraction, not stress in the same way as the acute accent in words like missão.

Both à noite and de noite exist, but they are not always used in exactly the same way.

A helpful general guide:

• à noite = at night / in the evening, often referring to when something happens
• de noite = by night / during the night, sometimes with a more general or habitual sense

For this sentence, A missão terminou à noite is the most natural choice because it answers When did it end?

Learners should usually start by using:

• de manhã
• à tarde
• à noite

These are very common and safe choices.

Not usually in this sentence.

Na noite means on the night of or in the night of, and it normally needs something more specific.

For example:

• na noite de sábado = on Saturday night
• na noite em que tudo mudou = on the night when everything changed

But for a general time expression like at night, Portuguese normally uses à noite, not na noite.

Yes. In many contexts, terminar can be translated as either to end or to finish.

So:

• A missão terminou = The mission ended.
• A missão terminou = The mission finished.

In English, ended often sounds slightly more natural for events, periods, or operations, while finished can also work. Portuguese uses terminar very naturally in both kinds of situations.

Yes, you could say À noite, a missão terminou.

Both are correct:

• A missão terminou à noite.
• À noite, a missão terminou.

The difference is mainly one of emphasis:

• A missão terminou à noite = neutral statement
• À noite, a missão terminou = extra focus on the time

Portuguese is a bit more flexible than English with word order, especially when moving time expressions.

The ending -ão is one of the sounds that English speakers often need to practise.

missão is roughly pronounced like mee-SOW̃, with:

• stress on the last syllable
• a nasal sound in -ão

Important points:

• ss gives an s sound, as in see
• ão is nasal, so it is not the same as a simple English ow

In European Portuguese, vowels are often less open and less fully pronounced than learners expect, so listening practice helps a lot here.

Both verbs can sometimes be translated as to end or to finish, but they are not always interchangeable in every context.

In this sentence, terminou is straightforward and very natural:

• A missão terminou à noite.

You might also hear:

• A missão acabou à noite.

That is also possible, but terminar often sounds a bit more neutral or formal, which fits well with a sentence like this.

So for learners:

• terminar = a very safe, standard choice for to end / to finish
• acabar = also common, but with wider uses depending on context

Because Portuguese often leaves out subject pronouns when the verb form already makes the meaning clear.

Here, terminou already tells us the subject is:

• he
• she
• it
• you (formal)

But since the noun A missão is already there, adding ela would be unnecessary.

So Portuguese naturally says:

• A missão terminou à noite.

Not:

• A missão ela terminou à noite. unless there is a special emphasis, and even then it would be unusual here.