Bạn bè nói chuyện lâu.

Bạn means friend. Bạn bè is a very common compound meaning friends in a collective sense, like one’s friends or a group of friends.

The second part, bè, helps give that group feeling. In modern Vietnamese, learners usually just memorize bạn bè as a set phrase.

Here, bạn bè is understood as plural or collective.

Vietnamese does not always mark plural the way English does, so you do not have to add những or các.

• Bạn bè nói chuyện lâu = natural
• Những bạn bè... = usually not how this phrase is used

If you want a more clearly countable phrase like the friends or some friends, Vietnamese often uses other structures, such as những người bạn.

Vietnamese does not have articles that work exactly like English a/an and the. A noun can often appear by itself, and context tells you whether it means something general, specific, or already known.

So Bạn bè nói chuyện lâu can mean something like:

• Friends talk for a long time
• The friends talked for a long time
• Friends are talking for a long time

The exact meaning depends on context.

Nói chuyện means to talk, to chat, or to have a conversation.

It is very common in everyday Vietnamese. It does not just mean say words; it means actual conversational talking.

Historically, it is made of:

• nói = speak / say
• chuyện = story / matter / topic

But in normal use, nói chuyện functions as a single verbal expression meaning talk/chat. It is best to learn it as one unit.

So in this sentence, you can think of:

• Bạn bè = subject
• nói chuyện = verb phrase
• lâu = duration word

Here, lâu means for a long time or long in a time sense.

Vietnamese often puts duration words after the verb:

• đợi lâu = wait a long time
• học lâu = study for a long time
• nói chuyện lâu = talk for a long time

So Bạn bè nói chuyện lâu follows a very normal pattern:

• subject + verb phrase + duration

Also, lâu is about time, not physical length. For physical length, Vietnamese often uses dài instead.

Vietnamese verbs do not change form for tense the way English verbs do. A sentence like this is tense-neutral by itself, so context decides.

Depending on the situation, it could mean:

• a general statement: Friends talk for a long time
• a description of a situation: The friends talked for a long time
• sometimes even a present situation, if the context makes that clear

If you want to make right now clearer, you can add đang:

• Bạn bè đang nói chuyện. = The friends are talking.

If you want to emphasize already for a long time, Vietnamese often uses lâu rồi:

• Bạn bè nói chuyện lâu rồi.

No. Nói chuyện is already complete by itself. It means to talk/chat, so it does not need a direct object.

If you want to say what they are talking about, you can add về:

• Bạn bè nói chuyện về công việc. = The friends talk about work.

They are related, but not identical:

• nói = say / speak
• nói chuyện = talk / chat
• trò chuyện = chat / converse

Nói chuyện is very common and everyday.
Trò chuyện is also natural, but can sound a little softer, warmer, or slightly more literary/formal depending on context.

So in this sentence, nói chuyện is a very normal choice.

A rough tone guide is:

• bạn — nặng tone, low and heavy
• bè — huyền tone, falling
• nói — sắc tone, rising
• chuyện — nặng tone, low and heavy
• lâu — ngang tone, level

A very rough English-style approximation is something like:

bahn beh noy chwee-uhn low

But that is only approximate. The tones are much more important than the English-like spelling.