Minha prima ficou solteira no ano passado e agora sai mais com as amigas.

Because ficar + adjective often means to become or to end up being.

So:

• ficou solteira = became single
• é solteira = is single

In this sentence, the idea is that her relationship status changed last year, so ficou is the natural choice.

Examples:

• Ela ficou doente. = She got sick.
• Ele ficou feliz. = He became happy / He was happy as a result.

Because solteira agrees with prima, which is a feminine noun.

Agreement in Portuguese is very important:

• primo solteiro = male cousin, single
• prima solteira = female cousin, single

So the adjective changes to match the gender and number of the noun.

Ficou is the preterite form of ficar for ela/você.

Here it means:

• she became
• she ended up
• she got

So Minha prima ficou solteira means My cousin became single.

Other common meanings of ficar depend on context:

• ficar em casa = to stay at home
• ficar com alguém = to hook up with / be with someone
• ficar pronto = to become ready

It is a very common and flexible verb.

No is a contraction of:

• em
  • o = no

So:

• no ano passado = in the past year / last year

Literally, it is something like in the year past, but the natural English translation is last year.

Other similar contractions:

• na = em + a
• nos = em + os
• nas = em + as

Examples:

• na semana passada = last week
• no mês passado = last month

Because sai is present tense, while saiu is past tense.

Here:

• agora sai mais = now she goes out more
• agora saiu mais would suggest now she went out more, which does not fit well here

The sentence contrasts past and present:

• no ano passado: she became single
• agora: now she goes out more

So sai shows a current, habitual action.

Yes, in this context sair means to go out.

So:

• ela sai com as amigas = she goes out with her friends

It usually means going out socially: meeting people, going to bars, restaurants, parties, etc.

Be careful: sair can also simply mean to leave or to come out, depending on context.

Examples:

• Ela saiu de casa cedo. = She left home early.
• O sol saiu. = The sun came out.
• Ela sai muito à noite. = She goes out a lot at night.

In Portuguese, the subject is often omitted when it is clear from context.

So this is completely natural:

• Minha prima ficou solteira no ano passado e agora sai mais com as amigas.

The subject of sai is still minha prima.

You could say:

• Minha prima ficou solteira no ano passado e agora ela sai mais com as amigas.

That is also correct, but repeating ela is not necessary.

Here mais means more, specifically more often.

So:

• agora sai mais = now she goes out more / more often

It does not necessarily mean she stays out longer or goes farther away. It usually means the frequency increased.

Examples:

• Agora estudo mais. = Now I study more.
• Ela fala mais. = She talks more.

Com as amigas means with the friends or more naturally with her friends / with her female friends in context.

Portuguese often uses the definite article where English would not.

So:

• com as amigas = with the friends / with her friends
• com amigas = with friends

The version with as sounds more like a known group of friends. Without the article, it sounds more general.

Also, amigas is feminine plural, so it specifically refers to female friends.

Yes. Amigas is feminine plural.

So:

• amigas = female friends
• amigos = male friends, or a mixed group of male and female friends

Since the sentence says as amigas, it specifically means she goes out more with her female friends.

Both are possible in Brazilian Portuguese.

• Minha prima = my cousin
• A minha prima = my cousin

Portuguese often allows a definite article before possessives, but it is not always required. In Brazil, both forms are common, depending on region, style, and level of formality.

So:

• Minha prima ficou solteira...
• A minha prima ficou solteira...

Both sound natural.

Yes, sair has some irregularity.

Present tense:

• eu saio
• você/ela sai
• nós saímos
• vocês/elas saem

Notice:

• eu saio has an extra o
• ela sai is short and very common

The word sai is pronounced as one syllable, roughly like English sigh.

Yes. Agora does not always mean right this second. It can also mean nowadays, these days, or at this point.

So in this sentence:

• agora sai mais com as amigas = now she goes out more with her friends

It contrasts her current lifestyle with the previous situation.

Similar use:

• Agora trabalho de casa. = Now I work from home.
• Agora ele lê mais. = Nowadays he reads more.

Not naturally. In English, got single is not idiomatic.

Better translations are:

• became single
• ended up single
• got divorced / broke up only if context specifically says that, which this sentence does not

So the safest translation is:

• My cousin became single last year...

Because ficou solteira only tells you the result: she was not single before, and then she was. It does not specify how that happened.