Vou passar na farmácia antes de voltar para casa.

On its own, passar often means to pass. But in everyday Brazilian Portuguese, passar em / passar na / passar no can mean to stop by or to drop in at a place.

So vou passar na farmácia does not usually mean I’m going to pass the pharmacy. It means I’m going to stop by the pharmacy.

A few similar examples:

• Vou passar no banco. = I’m going to stop by the bank.
• Passei na padaria. = I stopped by the bakery.

Vou passar is the very common spoken way to express the future in Brazilian Portuguese.

It is built with:

• vou = I go / I am going
• passar = infinitive

Together, vou passar means I’m going to stop by or simply I’ll stop by.

You could also say passarei na farmácia, but that sounds more formal or literary in many contexts. In everyday speech, Brazilians usually prefer vou passar.

Na is a contraction of:

• em = in / at
• a = the feminine singular definite article the

So:

• em + a = na

Because farmácia is a feminine noun, Portuguese often uses the article:

• a farmácia = the pharmacy
• na farmácia = at the pharmacy

This is a very common pattern.

In para casa, casa means home, and when Portuguese uses casa in that special sense, it often appears without an article after verbs of movement:

• ir para casa = to go home
• voltar para casa = to go back home
• chegar em casa = to arrive home

But if you mean a specific house/building, then the article can appear:

• Voltei para a casa da minha avó. = I went back to my grandmother’s house.

So here para casa means home, not to the house.

Because the subject is the same in both actions.

In the sentence:

• Vou passar na farmácia = I’m going to stop by the pharmacy
• antes de voltar para casa = before going back home

The person doing both actions is the same: I.

When the subject stays the same, Portuguese usually uses:

• antes de + infinitive

So:

• antes de voltar = before going back

If the subject changes, Portuguese often uses:

• antes que + subjunctive

Example:

• Vou sair antes que ele chegue. = I’m going to leave before he arrives.

Yes, you can.

• antes de voltar para casa is the more compact, natural version when the subject is obvious.
• antes de eu voltar para casa is also grammatical and adds emphasis or clarity.

In everyday speech, people often prefer the shorter form if there is no risk of confusion.

Not quite.

• ir à farmácia means to go to the pharmacy
• passar na farmácia suggests stopping by the pharmacy, often as one stop among others

So passar na farmácia can imply a quick errand or a stop on the way somewhere else.

In this sentence, that fits very well because the speaker is doing it before going home.

Portuguese often omits subject pronouns when the verb already makes the subject clear.

• vou clearly indicates eu
• so (eu) vou passar na farmácia is normally shortened to vou passar na farmácia

This is very natural in Portuguese.

Yes. In spoken Brazilian Portuguese, para is very often reduced to pra.

So these are both common:

• voltar para casa
• voltar pra casa

The full form para is slightly more careful or neutral in writing, while pra is very common in conversation and informal writing.

Because voltar para casa expresses movement toward a destination: to go back home.

• para shows direction: to / toward
• em casa means at home

So:

• voltar para casa = to return home
• estar em casa = to be at home

You can compare:

• Estou em casa. = I’m at home.
• Vou para casa. = I’m going home.

It connects to the action vou passar na farmácia.

The idea is:

• I’m going to stop by the pharmacy before going home

So antes de voltar para casa tells you when the stop at the pharmacy happens. It is not describing the pharmacy itself.

Yes, absolutely.

Depending on tone and context, natural English translations could include:

• I’m going to stop by the pharmacy before going home.
• I’ll stop by the pharmacy before I head home.
• I’m going to swing by the pharmacy before heading home.

That is because passar na farmácia is flexible and often sounds like a quick or casual stop.

A careful pronunciation would be close to:

vou passar na farmácia antes de voltar para casa

In natural speech, you may hear reductions such as:

• antes de sounding almost like antes dji in some accents
• para becoming pra
• vou passar na farmácia flowing together quite smoothly

A very natural spoken version might sound like:

• Vou passar na farmácia antes de voltar pra casa.

It breaks down like this:

• Vou passar = I’m going to stop by
• na farmácia = at the pharmacy
• antes de voltar = before going back
• para casa = home

So the overall pattern is:

[future expression] + [place] + [time clause]

That makes it a very useful model for other sentences, such as:

• Vou passar no mercado antes de ir pro trabalho.
• Vou passar no banco antes de voltar pra casa.