Se a impressora não funcionar, eu envio o arquivo pelo celular.

Se means if here. It introduces a condition:

• Se a impressora não funcionar... = If the printer doesn’t work...

This is a very common pattern in Portuguese for conditional sentences.

After se in a future-type condition, Portuguese usually uses the future subjunctive.

So:

• Se a impressora não funcionar... = If the printer doesn’t work / if the printer should fail to work...

For many regular -ar verbs, the future subjunctive looks exactly like the infinitive, so funcionar can be confusing because it looks like the dictionary form.

Compare:

• Ela não funciona. = It doesn’t work.
• Se ela não funcionar... = If it doesn’t work...

So this is not just an infinitive here; it is the correct verb form for this kind of conditional sentence.

In Portuguese, the present tense is often used to talk about the near future or a planned future action.

So:

• eu envio o arquivo literally looks like I send the file
• but in context it means I’ll send the file

This is very natural in Brazilian Portuguese. You could also say:

• eu enviarei o arquivo pelo celular

But that sounds a bit more formal or less conversational.

Yes, Portuguese often drops subject pronouns because the verb ending already shows the subject:

• Envio o arquivo pelo celular.

That would be perfectly natural.

But eu can still be included for:

• emphasis
• clarity
• contrast

In this sentence, eu envio may suggest something like I’ll send it as the solution to the problem.

So both are possible:

• Se a impressora não funcionar, envio o arquivo pelo celular.
• Se a impressora não funcionar, eu envio o arquivo pelo celular.

Portuguese uses definite articles much more often than English.

So a impressora literally means the printer, but in many everyday situations Portuguese prefers the article even where English might be less explicit.

This is very normal:

• A impressora não funciona. = The printer isn’t working.
• O celular está sem bateria. = The phone is out of battery.

For English speakers, the article can feel more frequent than expected.

In Portuguese, não normally goes directly before the verb it negates.

So:

• não funcionar = to not work / not work
• não envio = I do not send
• não tenho = I do not have

That is the standard position for negation.

Yes, it could be um arquivo, but the meaning changes.

• o arquivo = the file → a specific file already known from context
• um arquivo = a file → any file / a non-specific file

In your sentence, o arquivo suggests both speakers already know which file is being discussed.

So:

• eu envio o arquivo = I’ll send the file
• eu envio um arquivo = I’ll send a file

Pelo is the contraction of por + o:

• por o → pelo

Here, pelo celular means something like:

• by cellphone
• through the phone
• using the phone

So eu envio o arquivo pelo celular means the file will be sent via the cellphone, not with the printer.

Yes, but the nuance changes.

• pelo celular = via the cellphone / by cellphone
  Focuses on the means or channel.

• com o celular = with the cellphone
  Focuses more on the instrument used.

• no celular = on the cellphone
  Usually means something happening on the device itself, not necessarily the method of sending.

For this sentence, pelo celular is very natural because it emphasizes the method used to send the file.

Because the sentence begins with a conditional clause:

• Se a impressora não funcionar, ...

When this kind of clause comes first, Portuguese normally uses a comma before the main clause:

• Se chover, eu fico em casa.
• Se ele ligar, eu aviso você.

So the comma helps separate:

1. the condition
2. the result

Not only, but in this sentence that is the most natural meaning.

Arquivo can mean:

• a computer file
• an archive
• a file in an administrative/document sense

Because the sentence is about sending something by phone, arquivo is most naturally understood as a digital file.

It is mainly about the future.

Even though the main verb is in the present tense (envio), the whole sentence describes what the speaker will do if a future situation happens:

• If the printer doesn’t work, I’ll send the file by phone.

This use of present forms for future meaning is very common in Portuguese.

Usually not in this context.

• Se a impressora não funcionar is the normal form for a future possibility: If the printer doesn’t work
• Se a impressora não funciona sounds wrong or unnatural for this kind of future conditional

After se, when talking about a possible future event, Portuguese normally uses the future subjunctive, not the present indicative.

Yes. Funcionar is a regular -ar verb.

That is why its future subjunctive form looks simple:

• quando eu funcionar would not be used semantically, but the form is regular
• se ele funcionar
• se a impressora funcionar

For regular -ar verbs, the future subjunctive often looks identical to the infinitive, which is why learners sometimes think it is just the base form.