Mi prima está ilusionada porque le han ofrecido unas prácticas en una empresa muy fiable.

Because ilusionada describes a temporary emotional state, not a permanent characteristic.

• estar + adjective is often used for feelings, moods, and states:
  • está contenta
  • está nerviosa
  • está ilusionada

Using ser here would sound unnatural. In this sentence, the cousin is feeling excited/enthusiastic because of some good news.

No — this is a very important false friend.

In Spanish, estar ilusionado/a usually means:

• to be excited
• to be thrilled
• to be looking forward to something

So Mi prima está ilusionada means something like:

• My cousin is excited
• My cousin is really enthusiastic

It does not usually mean that she is under an illusion or mistaken.

Because it agrees with prima, which is feminine singular.

Spanish adjectives often change form to match the noun:

• mi primo está ilusionado
• mi prima está ilusionada

So here:

• prima = feminine singular
• ilusionada = feminine singular adjective

Le means to her here, and it refers to mi prima.

The verb ofrecer often works with an indirect object:

• Han ofrecido unas prácticas a mi prima
• Le han ofrecido unas prácticas

So the structure is:

• le = to her
• han offered
• unas prácticas = the thing being offered

In full, the idea is: They have offered her an internship/work placement.

Because Spanish normally includes the indirect object pronoun when saying offer someone something.

Compare:

• Han ofrecido unas prácticas a mi prima
• Le han ofrecido unas prácticas a mi prima

The pronoun le is very natural, and often expected, even if the person is also named later. In this sentence, mi prima appears earlier, so le clearly refers back to her.

Han ofrecido is the pretérito perfecto (present perfect):

• han = present of haber
• ofrecido = past participle of ofrecer

So:

• han ofrecido = have offered

In Spain, this tense is very commonly used for a past action that is connected to the present, especially if the result is still relevant now. That fits here perfectly: she is excited now because she has been offered an internship.

In many parts of Latin America, you might hear the simple past more often in similar contexts:

• le ofrecieron unas prácticas

But in Spain, le han ofrecido sounds very natural.

Yes. In Spanish, prácticas is often used in the plural to mean:

• an internship
• work placement
• professional training placement

So:

• hacer prácticas
• tener unas prácticas
• ofrecer unas prácticas

Even though English often uses a singular word like an internship, Spanish commonly uses the plural prácticas.

Do not translate it literally as practices in this context.

Unas here means something like some or a set of internship placements, but in English we usually would not translate it literally.

• unas prácticas = an internship / some internship work / a placement

Using unas makes the noun phrase sound complete and natural. Spanish often uses an article where English might not.

Compare:

• busca trabajo
• le han ofrecido unas prácticas

You could sometimes hear prácticas without the article in other contexts, but unas prácticas is very normal here.

Because porque is used to mean because.

Here the sentence gives the reason for her excitement:

• Está ilusionada porque...
• She is excited because...

Compare:

• porque = because
• por qué = why

Examples:

• Está contenta porque aprobó.
• ¿Por qué está contenta?

So in your sentence, porque is correct because it introduces the cause.

Fiable means:

• reliable
• trustworthy
• dependable

So una empresa muy fiable means: a very reliable/trustworthy company

Yes, fiable is very common in Spain. You may also see confiable in some places, especially in Latin America, but fiable is especially typical and natural in Spain Spanish.

This phrase simply means in a very reliable company.

Its parts are:

• en = in
• una empresa = a company
• muy fiable = very reliable

The adjective fiable comes after the noun, which is the normal position for most descriptive adjectives in Spanish:

• una empresa fiable
• una empresa muy fiable

That is more natural than trying to place the adjective before the noun.

Yes, absolutely.

That version is also very natural:

• A mi prima le han ofrecido unas prácticas en una empresa muy fiable.

Adding a mi prima makes the indirect object more explicit. Spanish often uses both:

• the pronoun: le
• and the full noun phrase: a mi prima

This is called clitic doubling, and it is very common in Spanish.

The original sentence starts with Mi prima está ilusionada..., so repeating a mi prima is not necessary there, because le is already enough.

It means female cousin specifically.

Spanish distinguishes gender here:

• primo = male cousin
• prima = female cousin

English usually just says cousin, unless the gender matters. So mi prima is:

• my cousin or, if you want to be more explicit,
• my female cousin

Mostly yes, but the exact English translation depends on context.

Here, ofrecer unas prácticas could be:

• to offer an internship
• to offer someone a placement
• to offer someone work experience

So le han ofrecido unas prácticas is literally they have offered her an internship, but a more natural English version might vary depending on context.

The core idea is that the company or another person has given her the opportunity to do the internship.