Se a senhora pagar pelo aplicativo, guarde o comprovante na pasta azul.

A senhora is a formal and respectful way to say you when speaking to a woman in Brazilian Portuguese.

So:

• a senhora = formal you (for a woman)
• você = neutral/common you
• tu = you in some regions, usually more informal

In this sentence, the speaker is probably being polite, such as in a customer-service, office, or medical setting.

Examples:

• Se a senhora pagar pelo aplicativo... = if you pay through the app...
• Se você pagar pelo aplicativo... = if you pay through the app...

Both can mean the same thing, but a senhora sounds more formal.

In Portuguese, when senhora, senhor, or senhorita are used like pronouns, they very often appear with the definite article:

• a senhora
• o senhor

So a senhora functions as a polite equivalent of you.

Without the article, senhora is more likely to sound like a form of address, similar to saying ma’am directly:

• Senhora, pode entrar. = Ma’am, you can come in.

But in your sentence, a senhora is the grammatical subject, so the article is natural and expected.

After se when talking about a future possibility or condition, Portuguese often uses the future subjunctive.

That is exactly what pagar is here.

• Se a senhora pagar... = If you pay...

This is one of the most common patterns in Portuguese:

• Se você precisar, me avise. = If you need to, let me know.
• Se ele vier, conversamos. = If he comes, we’ll talk.

For many regular verbs, the future subjunctive looks the same as the infinitive:

• pagar → pagar
• falar → falar
• comer → comer

So even though it looks like the dictionary form, here it is actually the future subjunctive, not just a plain infinitive.

Yes. Guarde is a command form: keep/save/store.

Because the sentence addresses a senhora (formal you), the command uses the third-person singular imperative, which has the same form as the present subjunctive:

• guarde = keep/save it

So:

• Se a senhora pagar pelo aplicativo, guarde o comprovante... = If you pay through the app, keep the receipt...

This is a formal command.

Compare:

• Guarda o comprovante. = Keep the receipt. (informal, often with *tu)*
• Guarde o comprovante. = Keep the receipt. (formal or *você/a senhora style)*

Yes. The subject is still understood as a senhora.

Portuguese often omits the subject pronoun or noun phrase when it is clear from context.

So this sentence really means:

• Se a senhora pagar pelo aplicativo, (a senhora) guarde o comprovante na pasta azul.

Repeating a senhora would be grammatical, but unnecessary and less natural in most contexts.

Pelo aplicativo means through the app, via the app, or using the app.

It does not usually mean for the app here.

This phrase is made of:

• por = by, through, via
• o aplicativo = the app

And por + o contracts into pelo:

• por + o = pelo

So:

• pelo aplicativo = through the app

Very common similar contractions:

• pela internet = through the internet
• pelo site = through the website
• pelo telefone = by phone

In Brazilian Portuguese, aplicativo usually means app, especially on a phone or computer.

So in everyday Brazilian Portuguese:

• aplicativo = app

It can correspond to English application, but in normal speech it is very often just app.

Examples:

• baixar um aplicativo = download an app
• pagar pelo aplicativo = pay through the app

Comprovante is a document or record that proves something happened, such as a payment, transfer, or registration.

Depending on context, it can be translated as:

• receipt
• proof of payment
• confirmation slip
• voucher

In this sentence, since the context is payment, receipt or proof of payment is a very natural translation.

Common expressions:

• comprovante de pagamento = proof of payment
• guardar o comprovante = keep the receipt / keep the proof

Because na is a contraction of:

• em + a = na

So:

• na pasta azul = in the blue folder

Also, be careful: pasta in Portuguese often means folder, file, or binder in office contexts. It is a common false friend for English speakers, because English pasta usually means food.

So here:

• pasta azul = blue folder

not blue pasta.

In Portuguese, adjectives usually come after the noun.

So:

• pasta azul = blue folder
• carro branco = white car
• casa grande = big house

This is the normal word order. Sometimes adjectives can come before the noun, but that often changes the tone or meaning. In your sentence, pasta azul is the standard and natural order.

Yes, absolutely. That would be a very natural Brazilian Portuguese sentence too.

The main difference is register:

• Se a senhora pagar... = formal, respectful
• Se você pagar... = neutral/everyday

Interestingly, the verb guarde stays the same with você:

• Se você pagar..., guarde...
• Se a senhora pagar..., guarde...

That is because both você and a senhora take third-person singular verb forms.

It is both:

1. Condition: Se a senhora pagar pelo aplicativo...
   = If you pay through the app...

2. Instruction/command: guarde o comprovante na pasta azul.
   = keep the receipt in the blue folder.

So the overall meaning is something like:

• If you pay through the app, keep the receipt in the blue folder.

This kind of structure is very common in instructions, customer support, office procedures, and formal notices.