Mi amiga se negó a contestar la pregunta enseguida y prefirió pensar un poco.

Because amiga is feminine and means female friend. Spanish nouns and adjectives often change form depending on gender:

• amigo = male friend
• amiga = female friend

So Mi amiga means my female friend.

Because negarse is the usual verb for to refuse.

• negar by itself usually means to deny
• negarse a + infinitive means to refuse to do something

So:

• negó la acusación = he/she denied the accusation
• se negó a contestar = he/she refused to answer

The se is part of the verb here, not a separate word with its own meaning.

Because negarse is followed by a + infinitive.

This is just the pattern you need to learn:

• negarse a hacer algo = to refuse to do something

So:

• se negó a contestar
• se negó a hablar
• se negó a entrar

Not every verb uses the same preposition before an infinitive, so this is an important construction to remember.

Both can mean to answer.

In this sentence, contestar la pregunta is completely natural and means to answer the question. You could also say responder a la pregunta.

A useful difference to remember is:

• contestar algo = answer something
• responder a algo = respond to something / answer something

So:

• contestar la pregunta
• responder a la pregunta

Both are correct, but the grammar pattern is slightly different.

Spanish often uses the definite article where English might not.

Here, la pregunta means the question, referring to a specific question already understood in the context.

Spanish uses articles more often than English, so contestar la pregunta sounds more natural than leaving the article out.

Enseguida usually means right away, immediately, or straight away.

In this sentence, it tells you that she refused to answer immediately and instead wanted time to think.

Depending on context, enseguida can sometimes feel slightly flexible, but here it clearly means without delay / on the spot.

They are in the preterite because the sentence describes completed actions in the past.

• se negó = she refused
• prefirió = she preferred

The speaker is telling us what happened as a finished event. The sequence is:

1. she refused to answer immediately
2. she preferred to think a little

That is why the preterite fits well.

Because preferir is followed directly by an infinitive, with no preposition.

Pattern:

• preferir + infinitive

So:

• prefirió pensar
• prefiero esperar
• prefieren salir

Compare that with negarse, which does need a:

• se negó a contestar

This is one of those verb patterns that learners simply need to memorise.

This is because preferir is a stem-changing verb.

In many present-tense forms, it changes:

• prefiero
• prefieres
• prefiere

In the preterite, third-person forms also change, but differently:

• preferí
• preferiste
• prefirió
• prefirieron

So e changes to i in prefirió. This is normal for -ir stem-changing verbs in the preterite.

Here pensar un poco means to think a little or to think for a bit.

It suggests she wanted a short amount of time to think before answering. In English, both of these sound natural:

• think a little
• think for a bit

So un poco can refer to a small amount or a short duration, depending on context. Here it gives the idea of briefly.

Spanish word order is flexible, and adverbs like enseguida can often move around.

Here, contestar la pregunta enseguida sounds natural and means to answer the question immediately.

You may also hear variations like:

• se negó a enseguida contestar — unnatural
• se negó a contestar enseguida la pregunta — possible, but less natural here
• se negó a contestar la pregunta enseguida — natural

So this placement is simply the most natural flow in this sentence.

Y means and. It links two past actions done by the same person:

• se negó a contestar la pregunta enseguida
• prefirió pensar un poco

So the sentence is basically saying:

• she refused to answer immediately
• and she preferred to think a bit

It connects the two related ideas smoothly.

A very close breakdown would be:

• Mi amiga = my female friend
• se negó = refused
• a contestar = to answer
• la pregunta = the question
• enseguida = right away
• y = and
• prefirió = preferred
• pensar = to think
• un poco = a little / for a bit

So a literal version would be:

My female friend refused to answer the question right away and preferred to think a little.

That helps show how the Spanish sentence is built.