Sau khi nói chuyện, chúng tôi quyết định thay đổi kế hoạch và ăn tối ở một quán gần bảo tàng.

Sau khi means after in the sense of after doing something.

In this sentence:

Sau khi nói chuyện, ...
= After talking / After having a conversation, ...

A very common pattern is:

sau khi + verb phrase

Examples:

• Sau khi ăn, tôi đi ngủ. = After eating, I went to sleep.
• Sau khi học xong, cô ấy về nhà. = After finishing studying, she went home.

So here, sau khi nói chuyện sets the time background for the main action.

Vietnamese often leaves out the subject when it is already understood from context.

In this sentence, the full idea is:

Sau khi (chúng tôi) nói chuyện, chúng tôi quyết định...

But repeating chúng tôi would sound unnecessary. Since the subject of the main clause is already chúng tôi, it is natural to understand that chúng tôi are also the ones doing the talking.

This is very common in Vietnamese, especially in subordinate clauses like:

• Sau khi ăn xong, tôi ra ngoài.
• Trước khi đi ngủ, cô ấy đọc sách.

Nói usually means to speak or to say.

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

So:

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

Examples:

• Tôi nói tiếng Việt. = I speak Vietnamese.
• Tôi nói với anh ấy. = I spoke to him.
• Chúng tôi nói chuyện với nhau. = We talked with each other.

In your sentence, nói chuyện is the more natural choice because it refers to having a discussion before making a decision.

This is an important Vietnamese pronoun distinction.

• chúng tôi = we, but not including the listener
• chúng ta = we, including the listener

So chúng tôi quyết định... means the speaker is talking about a group that made the decision, but the person being addressed is not part of that group.

A native English speaker often asks about this because English we does not normally make this distinction.

Quyết định means to decide.

In Vietnamese, it can be followed directly by another verb phrase, without any word equivalent to English to.

So:

chúng tôi quyết định thay đổi kế hoạch
literally: we decided change the plan

Natural English: we decided to change the plan

This pattern is very common:

• Tôi quyết định đi. = I decided to go.
• Cô ấy quyết định ở lại. = She decided to stay.

So Vietnamese does not need a separate word like English to after decide.

Yes. In this sentence, quyết định governs both actions:

• thay đổi kế hoạch
• ăn tối ở một quán gần bảo tàng

So the meaning is:

We decided [to change the plan] and [to eat dinner at a place near the museum].

This is a normal structure in Vietnamese. One verb like quyết định can be followed by multiple coordinated actions joined by và.

Because thay đổi is being used here as a verb meaning to change, and kế hoạch is its object.

So:

thay đổi kế hoạch = change the plan

This follows normal Vietnamese word order:

verb + object

• ăn cơm = eat rice / eat a meal
• đọc sách = read a book / read books
• thay đổi kế hoạch = change the plan

If you say kế hoạch thay đổi, that means the plan changes / the plan changed, where kế hoạch is the subject.

So the two patterns are different:

• thay đổi kế hoạch = change the plan
• kế hoạch thay đổi = the plan changes

Ăn tối means to eat dinner / have dinner.

This is a very common Vietnamese expression:

• ăn sáng = have breakfast
• ăn trưa = have lunch
• ăn tối = have dinner

Even though ăn literally means eat, in these combinations it corresponds to English have in many cases.

So:

• ăn tối ở một quán... = have dinner at an eatery...

You could also hear ăn bữa tối, but ăn tối is shorter and very natural in everyday Vietnamese.

Here ở means at.

So:

ăn tối ở một quán
= have dinner at a restaurant/eatery

Ở is very common for location:

• Tôi ở nhà. = I am at home.
• Cô ấy làm việc ở Hà Nội. = She works in Hanoi.
• Chúng tôi ăn ở quán này. = We eat at this place.

In your sentence, it introduces the place where the dinner happens.

Quán usually refers to a small eating or drinking place, depending on context. It can mean something like:

• eatery
• café
• food stall
• casual restaurant
• shop, in some contexts

So một quán gần bảo tàng means a place/eatery near the museum.

Compared with nhà hàng, quán often sounds more casual and less formal.

Roughly:

• quán = casual place
• nhà hàng = restaurant, often more formal

No, quán here is a normal noun, not a classifier.

Một quán simply means a/an eatery / one eatery.

Vietnamese classifiers are words like:

• một cái bàn = a table
• một con mèo = a cat
• một quyển sách = a book

But quán itself is the thing being counted, so no separate classifier is needed here.

Gần means near.

So:

một quán gần bảo tàng
= a place near the museum

Vietnamese does not have articles like English a and the in the same way. Whether something is definite or indefinite is often understood from context.

So bảo tàng can mean:

• museum
• the museum

depending on the situation.

Also, gần goes directly before the noun:

• gần nhà = near home
• gần trường = near school
• gần bảo tàng = near the museum

The comma separates the introductory time clause from the main clause.

Structure:

• Sau khi nói chuyện, = After talking,
• chúng tôi quyết định... = we decided...

This is similar to English:

• After talking, we decided...

In Vietnamese writing, this comma is very natural when a time phrase or subordinate clause comes at the beginning of the sentence.

Vietnamese often does not mark tense explicitly if the time is clear from context.

In this sentence, the sequence of events makes the past interpretation natural:

1. they talked
2. they decided
3. they ate or planned to eat dinner

Because of the context, English translates it naturally in the past.

If needed, Vietnamese could add time markers like:

• đã for past/completed action
• sẽ for future
• đang for ongoing action

For example:

• Sau khi nói chuyện, chúng tôi đã quyết định...

But very often these markers are omitted when the meaning is already clear.