Vamos conversar depois do jantar.

Literally, vamos conversar is we go to talk / we are going to talk, but in real Brazilian Portuguese it often works like let’s talk or we’ll talk depending on context.

In this sentence, it sounds like a natural suggestion or plan:

• Vamos conversar depois do jantar. = Let’s talk after dinner / We’ll talk after dinner

So vamos + infinitive is a very common pattern for making suggestions or talking about an intended action.

Because after vamos, Portuguese normally uses another verb in the infinitive.

Pattern:

• vamos + infinitive

Examples:

• Vamos comer. = Let’s eat.
• Vamos sair. = Let’s go out.
• Vamos conversar. = Let’s talk.

So conversar stays in its base form because it follows vamos.

Yes, you could say Conversaremos depois do jantar, but it sounds more formal and less conversational.

In everyday Brazilian Portuguese, speakers usually prefer:

• Vamos conversar depois do jantar
• A gente conversa depois do jantar
• A gente vai conversar depois do jantar

So the sentence you were given sounds very natural in spoken Brazilian Portuguese.

Not always. Vamos is the we form of ir (to go), so by itself it can literally mean we go.

But when it is followed by another verb in the infinitive, it often means:

• let’s ...
• we’re going to ...
• sometimes simply we’ll ...

For example:

• Vamos ao cinema. = We’re going / let’s go to the movies.
• Vamos conversar. = Let’s talk.

So the structure around vamos matters.

Both can relate to speaking, but they are not exactly the same.

• conversar = to have a conversation, to chat, to talk with someone
• falar = to speak, to say, to talk

In this sentence, conversar fits well because it suggests an exchange between people, not just one person speaking.

Compare:

• Vamos conversar depois do jantar. = Let’s talk/chat after dinner.
• Vamos falar sobre isso depois do jantar. = Let’s talk about that after dinner.

So falar is often used when there is a topic, especially with sobre:

• falar sobre... = talk about...

Word by word:

• depois = after
• do = of the / after the, depending on context
• jantar = dinner

So:

• depois do jantar = after dinner / more literally after the dinner

In English, we usually do not say after the dinner in this kind of sentence, but Portuguese often uses the article.

Because de + o contracts into do in Portuguese.

This is a very common contraction:

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

So:

• de o jantar becomes do jantar

You should think of do as a normal, necessary contraction, not as optional fancy grammar.

Here it is a noun, meaning dinner.

That may be confusing because jantar can also be a verb:

• jantar = to have dinner / to dine

How do we know it is a noun here? Because it is preceded by the article hidden inside do:

• do jantar = de + o jantar
• that o shows we are talking about the noun the dinner / dinner

Compare:

• Vamos jantar. = Let’s have dinner. → verb
• Depois do jantar. = After dinner. → noun

Portuguese often leaves out subject pronouns when the verb already makes the subject clear.

• vamos already tells you the subject is nós (we)

So:

• Nós vamos conversar depois do jantar.
• Vamos conversar depois do jantar.

Both are correct, but the second is more natural unless you want emphasis.

This is very common in Portuguese because verb endings often show who the subject is.

Yes, absolutely. That version is also natural.

Compare:

• Vamos conversar depois do jantar.
• Depois do jantar, vamos conversar.

Both mean the same thing. The second version puts more focus on the time expression after dinner.

Portuguese word order is fairly flexible in sentences like this, especially when moving a time phrase to the beginning.

The original sentence is already natural, but in everyday speech you might also hear:

• A gente conversa depois do jantar.
• A gente vai conversar depois do jantar.
• Vamos conversar depois do jantar, tá?

A few notes:

• a gente is very common in Brazil for we
• vamos conversar sounds a little like a suggestion or decision
• a gente conversa can sound a bit softer and more casual

So your sentence is perfectly good and natural, especially if someone is proposing that the conversation happen later.