O primeiro tempo terminou sem gols.

Usually, yes: tempo often means time or weather. But in sports, it can also mean a half or period.

In Brazilian soccer, o primeiro tempo means the first half and o segundo tempo means the second half.

O is the masculine singular definite article, so it means the.

Portuguese uses definite articles more often than English does. Here, we are talking about a specific part of a specific match, so o primeiro tempo is the natural full form. Without o, it can sound more like a headline, note, or label than a normal sentence.

Because primeiro has to agree with tempo.

• tempo is masculine singular
• so the ordinal must also be masculine singular: primeiro

If the noun were feminine, you would use primeira:

• a primeira parte
• a primeira etapa

Ordinal numbers such as primeiro, segundo, terceiro usually come before the noun in Portuguese when naming order or sequence.

So:

• o primeiro tempo
• o segundo gol
• a primeira vez

That is the normal word order here.

Terminou is the pretérito perfeito of terminar, third person singular.

It is used for a completed action in the past. In this sentence, it tells you that the first half ended as a finished event.

So this is the normal tense for match reports, narrating events, or stating results.

Because terminou presents the ending as a single completed event.

Terminava is the imperfect tense, which usually gives a different feeling: something ongoing, habitual, descriptive, or backgrounded.

In a sports result sentence, terminou is the expected choice because the speaker is reporting a completed fact.

Portuguese often does not need an extra subject pronoun when the subject is already clear.

Here, the subject is explicitly stated: o primeiro tempo. So adding ele would usually be unnecessary.

English often repeats the subject with a pronoun in later clauses, but Portuguese is more comfortable leaving it out when it is obvious.

Sem means without.

So sem gols literally means without goals.

The plural gols is natural because the idea is that there were zero goals in total. With countable nouns, Portuguese often uses the plural after sem when talking about the absence of something:

• sem problemas
• sem erros
• sem gols

Yes. In Brazilian Portuguese, the normal word is gol, and the plural is gols.

A useful variety note:

• Brazil: gol / gols
• Portugal: golo / golos

So this sentence is clearly in Brazilian Portuguese style.

Yes, absolutely. Acabou also works well here.

Both are natural:

• O primeiro tempo terminou sem gols.
• O primeiro tempo acabou sem gols.

Terminou can sound a bit more neutral or report-like. Acabou can sound a bit more conversational. In real Brazilian usage, both are common.

A rough pronunciation guide is:

u pre-MEI-ru TEM-pu ter-mi-NOU sem GOWS

A few helpful notes:

• The initial o often sounds more like u in normal speech.
• primeiro is stressed on mei.
• terminou is stressed on the last syllable.
• sem has a nasal sound.
• In many Brazilian accents, the l in gol sounds like a w-like glide, so gol sounds close to gow.