Eu falei com ela através do aplicativo.

Falei is the 1st person singular form of the verb falar in the pretérito perfeito (the simple past in Portuguese).

So:

• eu falei = I spoke / I talked
• infinitive: falar = to speak / to talk

In this sentence, eu falei tells you that the action happened at a specific time in the past.

Examples:

• Eu falei com ela ontem. = I talked to her yesterday.
• Eu falo com ela todos os dias. = I talk to her every day.

So falei is past, while falo is present.

You can omit eu in most cases.

Portuguese often drops subject pronouns when the verb already makes the subject clear. Since falei clearly means I spoke, eu is optional.

So both are natural:

• Eu falei com ela através do aplicativo.
• Falei com ela através do aplicativo.

Including eu can add:

• emphasis
• contrast
• extra clarity in context

For example:

• Eu falei com ela, não ele. = I spoke with her, not him.

Because the verb falar can be used with com when the idea is to talk with someone.

• falar com alguém = to talk/speak with someone

So:

• Eu falei com ela = I spoke with her / I talked to her

You may also hear:

• falar a alguém in some contexts, especially in more formal or specific usage, but for everyday Brazilian Portuguese, falar com alguém is extremely common and natural.

For a learner, falar com + person is the safest pattern to remember.

After a preposition like com, Portuguese uses a stressed pronoun, not a direct-object pronoun.

So:

• com ela = with her
• com ele = with him
• comigo = with me
• com você = with you

That is why ela appears here, not a or lhe.

Compare:

• Eu vi ela. = I saw her.
• Eu falei com ela. = I spoke with her.

In your sentence, ela is part of the prepositional phrase com ela.

Através de means through, by means of, or via, depending on context.

In this sentence:

• através do aplicativo = through the app / via the app

Literally, através often suggests through something, but in modern usage it is also commonly used to mean by means of.

So the sentence means that the app was the medium used for the communication.

Because Portuguese normally contracts de + o into do.

So:

• de + o = do
• de + a = da
• de + os = dos
• de + as = das

Since the expression is através de and the noun is o aplicativo, you get:

• através de + o aplicativo
• através do aplicativo

This kind of contraction is very common in Portuguese.

Yes. In Brazil, aplicativo is the standard word for app or application.

Examples:

• Baixei um aplicativo novo. = I downloaded a new app.
• Esse aplicativo é muito bom. = This app is very good.

In casual speech, Brazilians may also say just:

• app

But aplicativo is fully normal and very common.

Yes, absolutely. Pelo aplicativo is very natural in Brazilian Portuguese.

Compare:

• através do aplicativo = through the app / via the app
• pelo aplicativo = through the app / on the app / via the app

In everyday speech, many Brazilians would probably prefer pelo aplicativo, because it often sounds more direct and idiomatic in this kind of context.

Examples:

• Eu falei com ela pelo aplicativo.
• Eu mandei a mensagem pelo aplicativo.

So your original sentence is correct, but pelo aplicativo may sound more conversational.

The original order is natural:

• Eu falei com ela através do aplicativo.

But Portuguese allows some flexibility. You could also say:

• Eu falei com ela pelo aplicativo.
• Através do aplicativo, eu falei com ela.
• Eu falei através do aplicativo com ela.

However, not all versions sound equally natural. In everyday Brazilian Portuguese, the most natural choices are usually:

• Eu falei com ela através do aplicativo.
• Eu falei com ela pelo aplicativo.

Putting com ela right after falei is especially common because falar com alguém is a strong, familiar unit.

It can mean either, depending on context.

Falar com alguém is broad. It can refer to:

• speaking in a call
• talking in person
• chatting by audio
• sometimes even exchanging messages, depending on the situation

Because the sentence includes através do aplicativo, it suggests the communication happened using an app, but it does not specify exactly whether it was:

• a voice call
• video call
• voice message
• text chat

Context tells you that part.

A natural Brazilian pronunciation would sound roughly like:

eu fa-LEI côm EH-la a-tra-vés du a-pli-ca-TI-vu

A few useful notes:

• falei has stress on the last syllable: fa-LEI
• através has stress on vés
• do is usually pronounced like du in normal Brazilian speech
• ela often sounds like EH-la
• com may sound like cõ with a nasal quality

In fast speech, the sentence flows smoothly, something like:

Eu falei com ela através do aplicativo.

with the rhythm grouping around:

• Eu falei
• com ela
• através do aplicativo

Yes. In natural English, talked to her, talked with her, and spoke with her can all work.

The Portuguese falei com ela does not force one exact English verb choice. Depending on tone, you could translate it as:

• I spoke with her through the app.
• I talked to her through the app.
• I talked with her on the app.
• I contacted her through the app. (a bit broader and less literal)

So the Portuguese structure stays the same, while the best English translation depends on style and context.