A operação terminou bem.

A is the feminine singular definite article, meaning the.

It is used because operação is:

• feminine
• singular
• a specific operation, not just any operation

So:

• a operação = the operation

If it were masculine, you would use o instead.

In Portuguese, every noun has a grammatical gender, usually masculine or feminine.
Operação is simply a feminine noun, so it takes feminine forms like:

• a operação
• uma operação

Many nouns ending in -ção are feminine in Portuguese, for example:

• a nação
• a informação
• a situação

So operação follows a very common pattern.

Terminou is the 3rd person singular of the verb terminar in the pretérito perfeito (the simple past).

That means it refers to a completed action in the past:

• terminar = to finish / to end
• terminou = finished / ended

Here it agrees with a operação, which is a singular subject:

• A operação terminou = The operation ended / finished

Other forms of terminar in the same tense:

• eu terminei
• tu terminaste
• ele/ela terminou
• nós terminámos
• vocês/eles terminaram

In European Portuguese, nós terminámos is especially useful because the accent helps distinguish it from the present terminamos.

Because bem is an adverb, and here it describes how the action ended.

• bem = well
• boa = good (feminine adjective)

Adverbs modify verbs, while adjectives modify nouns.

So:

• A operação terminou bem. = The operation ended well.
  Here bem modifies terminou.

But:

• A operação foi boa. = The operation was good.
  Here boa describes the noun operação.

This is the same basic difference as well vs good in English.

They are similar, but not exactly the same.

• terminou bem focuses on the ending: the operation ended well
• correu bem focuses on the overall course/result: the operation went well

So:

• A operação terminou bem. = the final outcome was good
• A operação correu bem. = the whole operation went smoothly / was successful

In many real situations, both are possible, but the nuance is slightly different.

No. Operação can mean different kinds of operation, depending on context.

It can refer to:

• a surgical operation
• a military operation
• a police operation
• a mathematical operation
• a business or technical operation

So the sentence could be medical, but it does not have to be. The context tells you which kind of operation is meant.

The most natural neutral order in Portuguese is:

subject + verb + adverb

So:

• A operação terminou bem.

A different order, such as Bem terminou a operação, is possible only in very marked or literary contexts, and it sounds unnatural in everyday speech.

For a learner, the safest pattern is:

• A reunião terminou bem.
• O jogo acabou mal.
• A conversa correu bem.

In other words, put bem after the verb unless you have a special reason not to.

In European Portuguese, operação is approximately pronounced:

oo-pe-ra-SOUNG

More precisely, the ending -ção is very common and sounds roughly like:

• -são / -sɐ̃w̃

A few useful pronunciation points:

• ç sounds like s
• ão is nasal
• unstressed vowels are often reduced in European Portuguese

So the full sentence in Portugal sounds roughly like:

A operação terminou bem.
≈ uh oo-pe-ra-SOUNG tehr-mee-NOH bayng

That spelling is only approximate, but it may help you recognise it.

They show pronunciation and correct spelling.

• ç tells you the letter is pronounced like s, not like k
• ã shows a nasal vowel
• the written accent in operação helps mark the stressed syllable pattern and proper spelling

This -ção ending is extremely common in Portuguese and usually corresponds to English words ending in:

• -tion
• -sion

Examples:

• informação = information
• nação = nation
• operação = operation

So learning -ção as a chunk is very useful.

Normally, no. In standard Portuguese, you would usually say:

• A operação terminou bem.

Leaving out the article sounds incomplete or unnatural in an ordinary sentence. Portuguese uses definite articles more often than English does.

You might see article omission in:

• headlines
• notes
• very telegraphic style

But in normal speech and writing, keep the article here.

Yes, often you can.

• A operação terminou bem.
• A operação acabou bem.

Both can mean that the operation ended well. However, terminou often sounds a little more neutral or formal, while acabou can sound slightly more everyday.

In many contexts, the difference is small. A learner can safely understand both.