O almoço não custou muito, porque hoje havia desconto no aplicativo.

Custou is the simple past (preterite) form of custar, which means to cost.

In this sentence, o almoço não custou muito means the cost of the lunch is being described as a completed past fact.

A quick breakdown:

• custar = to cost
• custou = it cost

It is 3rd person singular because the subject is o almoço.

Here, muito means much / a lot, not very.

So:

• não custou muito = it didn’t cost much

This is because muito is modifying the verb custou.

Compare:

• custou muito = it cost a lot
• muito caro = very expensive

So muito can mean different things depending on what it is modifying:

• with a verb: much / a lot
• with an adjective or adverb: very

Porque means because.

In this sentence:

• porque hoje havia desconto no aplicativo = because there was a discount on the app today

This is the standard form used for giving a reason.

A very common learner point is the difference between these forms:

• porque = because
• por que = why / for what reason
• porquê = the reason
• por quê = why, when it comes at the end

So here, since the sentence is giving an explanation, porque is the correct form.

Here, havia means there was.

It comes from the verb haver, which can be used to express existence:

• havia desconto = there was a discount

So the second part of the sentence means:

• hoje havia desconto no aplicativo = today there was a discount on the app

In Brazilian Portuguese, this use of haver is correct and fairly common, especially in more neutral or slightly more formal language.

Both can express the idea of there was / there were in Brazilian Portuguese, but they have different tones.

• havia desconto sounds more standard, neutral, or written
• tinha desconto sounds more colloquial and conversational

So:

• hoje havia desconto no aplicativo = slightly more formal/neutral
• hoje tinha desconto no aplicativo = very common in everyday speech

A Brazilian speaker would understand both perfectly.

Havia is the imperfect form of haver.

In this sentence, it gives background information explaining why the lunch did not cost much. It describes the situation that existed at that time:

• today there was a discount on the app

Using houve is possible in some contexts, but it sounds more like a completed event or fact:

• houve desconto = there was a discount / a discount took place

Using havia here feels more like describing a condition that was in effect, which fits the explanation after porque.

Portuguese often leaves out the article after existential verbs like haver when the idea is general:

• havia desconto = there was discount / there was a discount available

This sounds natural in Portuguese, even though English usually prefers a discount.

You can also say:

• havia um desconto

That would sound a little more specific, as if you are emphasizing one particular discount.

So:

• havia desconto = more general, natural
• havia um desconto = also correct, slightly more specific

No aplicativo means in the app or on the app.

It is a contraction:

• em + o = no

So:

• no aplicativo = in/on the app

Portuguese often uses em where English uses on with digital platforms:

• no aplicativo = on the app
• no site = on the website
• na internet = on the internet

Also, aplicativo is the normal Brazilian Portuguese word for app or mobile app.

Portuguese uses definite articles more often than English.

Here, o almoço refers to a specific lunch, so the article sounds natural:

• o almoço não custou muito = the lunch / lunch didn’t cost much

In English, we often omit the article and just say lunch, but Portuguese usually prefers the article when the noun is the subject and refers to a specific thing.

So even if English says simply lunch, Portuguese often says:

• o almoço
• o jantar
• o café da manhã

Yes, it is natural.

It sounds clear and correct, with a slightly neutral or mildly written tone because of havia.

A more everyday spoken version might be:

• O almoço não custou muito, porque hoje tinha desconto no aplicativo.

Another very natural version would be:

• O almoço não saiu muito caro, porque hoje tinha desconto no aplicativo.

So the original sentence is good Portuguese, and a Brazilian speaker would have no problem with it.

A rough pronunciation guide in English-friendly spelling could be:

oo aw-MOH-soh now koos-TOH MOOY-too, por-KEH OH-zhee ah-VEE-ah des-KON-too noo ah-plee-kah-CHEE-voo

A few notes:

• almoço has ç, which sounds like s
• não has a nasal sound, roughly like now said through the nose
• hoje sounds roughly like OH-zhee
• aplicativo in Brazil usually has a chee sound in ti before i

This is only approximate, but it is a useful starting point.