Mi hermana fue a la zapatería porque quería unas sandalias cómodas para la fiesta.

Mi hermana is the normal, neutral way to say my sister in everyday Spanish.

Hermana mía also exists, but it is much more emphatic, emotional, poetic, or contrastive. It can sound like my own sister! or be used in dramatic speech.

So in an ordinary sentence, Mi hermana is the natural choice.

The verb ir normally uses a before a destination.

• ir a + place = to go to + place

So:

• fue a la zapatería = she went to the shoe shop

This is one of the most basic patterns in Spanish:

• Voy al supermercado
• Fuimos a Madrid
• Iban a casa

Fue is the preterite of ir, and it presents the action as a completed event:

• Mi hermana fue a la zapatería = she went to the shop

This sounds like a finished action in the story.

Iba is the imperfect, which would usually suggest an ongoing, habitual, or background action:

• Mi hermana iba a la zapatería cuando... = My sister was going to the shoe shop when...
• Mi hermana iba a la zapatería los sábados = My sister used to go to the shoe shop on Saturdays

So fue is used because this is a specific completed trip.

This is a very common learner question.

Here, quería is in the imperfect because it describes a background desire, intention, or state of mind:

• porque quería unas sandalias cómodas = because she wanted some comfortable sandals

The wanting is not presented as a single completed event. It is the reason behind her action.

If you said quiso, it would sound more like she tried to want / she came to want / she decided to want, depending on context, and it is usually less natural here.

A common storytelling pattern in Spanish is:

• preterite for the main action: fue
• imperfect for the reason, background, or mental state: quería

The accent mark in quería shows where the stress goes:

• que-rí-a

Without the accent, the pronunciation and spelling rules would point differently. In Spanish, written accents are important because they show the correct stressed syllable and can distinguish forms.

Also, quería is an imperfect form of querer:

• yo quería
• él/ella quería
• nosotros queríamos

Unas is the feminine plural form of the indefinite article. It can mean:

• some
• a pair of
• sometimes just a natural, slightly less bare way of referring to plural countable objects

So quería unas sandalias cómodas means she wanted some comfortable sandals or a pair of comfortable sandals.

You could sometimes omit the article in Spanish, but here unas sandalias sounds very natural and idiomatic.

Zapatería is a feminine noun, so it takes la.

Many nouns ending in -ía are feminine:

• la zapatería
• la panadería
• la cafetería

A zapatería is a shoe shop or shoe store.

Adjectives in Spanish usually agree with the noun in gender and number.

Here:

• sandalias is feminine plural
• so the adjective must also be feminine plural
• therefore: cómodas

Compare:

• un zapato cómodo = masculine singular
• unos zapatos cómodos = masculine plural
• una sandalia cómoda = feminine singular
• unas sandalias cómodas = feminine plural

The accent mark shows the stress:

• CÓ-mo-das

It is the feminine plural form of cómodo.

The different forms are:

• cómodo
• cómoda
• cómodos
• cómodas

The written accent stays in all these forms.

This is a classic por vs para question.

Here, para expresses purpose or intended use:

• sandalias cómodas para la fiesta = comfortable sandals for the party

In other words, the sandals are intended to be worn at the party.

Por la fiesta would usually mean something more like:

• because of the party
• around the party
• through the party area, depending on context

So para is the correct choice when talking about what something is meant for.

Porque as one word means because and introduces a reason:

• Fue a la zapatería porque quería...

Spanish also has similar-looking forms that mean different things:

• porque = because
• por qué = why
• el porqué = the reason
• por que = less common combination in other structures

In this sentence, it is clearly the conjunction because, so it is porque.

In Spanish, adjectives often come after the noun, especially when they are simply describing a quality in a neutral way.

So:

• sandalias cómodas = comfortable sandals

This is the most normal order here.

Sometimes Spanish adjectives can come before the noun, but that often changes the tone or meaning. For ordinary descriptive use, noun + adjective is very common.

Yes. In English, the best translation may vary by region:

• shoe shop
• shoe store

For a learner of Spanish from Spain, zapatería is the standard word for a place that sells shoes.

This is an important point because fue can be a form of both ir and ser.

• fue = went from ir
• fue = was from ser

You know which one it is from the context.

Here, fue a la zapatería must be from ir, because:

• ir commonly goes with a + place
• ser a la zapatería would not make sense here

So in this sentence, fue clearly means went.

Yes, but the meaning changes slightly.

• fue a la zapatería suggests a specific shoe shop, often one known in the context, or simply the shoe shop
• fue a una zapatería means she went to a shoe shop, with less specificity

Both are grammatically correct. The original sentence uses la zapatería, which sounds like a particular or contextually identifiable shop.