Mi hermana se probó una blusa blanca y una rebeca gris para la entrevista.

Because probarse means to try on clothes, while probar by itself usually means to try, to test, or to taste something.

• probar = to try/test/taste
• probarse = to try on

In this sentence, se shows that your sister tried the clothes on herself:

• Mi hermana se probó una blusa... = My sister tried on a blouse...

With clothing, Spanish very often uses this reflexive form.

Probó is the preterite form of probarse for ella:

• yo me probé
• tú te probaste
• él/ella se probó

The preterite is used here because it describes a completed action in the past: she tried the clothes on.

The accent in probó shows both pronunciation and meaning.

• probó = he/she tried
• probo without an accent is not the same verb form

The stress falls on the last syllable: pro-BÓ.

This is very common in Spanish past-tense forms:

• habló
• comió
• vivió

Because Spanish normally repeats the article when talking about two separate countable items:

• una blusa blanca y una rebeca gris

This makes it clear that they are two different garments.

In English, a white blouse and a grey cardigan also works with only one a, but Spanish often sounds more natural repeating the article here.

In Spain, rebeca means a cardigan.

It’s a common Spain Spanish word for a knitted jacket or sweater that opens at the front. In other Spanish-speaking places, people may use different words, such as cárdigan or suéter, depending on the region.

So this sentence is very natural for Spanish from Spain.

In Spanish, descriptive adjectives usually come after the noun.

So:

• blusa blanca = white blouse
• rebeca gris = grey cardigan

That is the normal word order. In English, adjectives usually come before the noun, but Spanish commonly places them after.

Because adjectives must agree with the noun in gender and number, but some adjectives have the same form for masculine and feminine.

• blusa is feminine singular, so blanco becomes blanca
• rebeca is also feminine singular, but gris does not change for gender

Examples:

• camisa blanca
• pantalón blanco
• falda gris
• abrigo gris

For the plural:

• blusas blancas
• rebecas grises

In modern Spanish, you normally use the possessive directly before the noun:

• mi hermana = my sister

Spanish does not usually say la mi hermana in standard modern usage. The article is not used there.

The short possessives are:

• mi / mis
• tu / tus
• su / sus
• nuestro/a/os/as
• vuestro/a/os/as in Spain

Para here means for, expressing purpose or intended use.

So:

• para la entrevista = for the interview

It tells us why she tried on the clothes: she was choosing or checking them for that occasion.

This is a very common use of para:

• para la fiesta
• para el trabajo
• para la boda

Spanish often uses the definite article (el, la, los, las) when the context already makes it clear whose thing or event it is.

So para la entrevista sounds natural even though in English we might say for her interview.

Using su entrevista is possible, but it would put more emphasis on the fact that the interview is hers. In many everyday situations, Spanish prefers the simpler la entrevista.

By itself, the sentence does not fully specify that. It simply says she tried on a white blouse and a grey cardigan.

It could mean:

• she tried both items on as an outfit, or
• she tried each one on during the same shopping/choosing moment

Context would decide. Most listeners would probably understand that she was considering those clothes for the interview, possibly together.

Grammatically, probar without se exists, but with clothing Spanish usually prefers probarse when a person tries clothes on themselves.

So:

• Mi hermana se probó una blusa... = natural for tried on
• Mi hermana probó una blusa... may sound incomplete or less natural in this context

For clothes, the reflexive form is the safer choice.

Not exactly.

• blusa usually means blouse, typically a women’s top
• camisa usually means shirt

In this sentence, blusa is the correct word if the garment is a blouse rather than a shirt.

Yes. Entrevista is the general word for interview.

Depending on context, it could be:

• a job interview
• a media interview
• an academic interview

In this sentence, many learners would naturally interpret la entrevista as a job interview, especially because trying on clothes fits that situation well.