Lan không biết đường đến ngân hàng nên mở bản đồ trên điện thoại.

It means not know the way / not know the route.

Even though biết usually means to know, the expression biết đường is very common for knowing how to get somewhere. So Lan không biết đường đến ngân hàng means Lan does not know how to get to the bank.

It is more natural than translating word-for-word as Lan does not know the road.

Yes, đường has several meanings depending on context:

• road / street
• way / route
• sugar

Here, because it is followed by đến ngân hàng, it clearly means the way / route to the bank.

So in this sentence, đường is best understood as route rather than a specific physical street.

Here đến means to or leading to.

So:

• đường đến ngân hàng = the way to the bank
• literally: route leading to the bank

This is a very normal Vietnamese structure. You can think of it as:

• đường đến trường = the way to school
• đường đến sân bay = the way to the airport

Nên means so, therefore, or as a result.

It connects the first idea and the second idea:

• Lan không biết đường đến ngân hàng = Lan doesn’t know the way to the bank
• nên mở bản đồ trên điện thoại = so she opens the map on her phone

So the structure is:

cause + nên + result

It is not exactly the same as because. For because, Vietnamese usually uses vì or bởi vì.

For example:

• Vì Lan không biết đường đến ngân hàng nên cô ấy mở bản đồ trên điện thoại.

That means Because Lan didn’t know the way to the bank, she opened the map on her phone.

Because Vietnamese often drops repeated subjects when they are already clear from context.

In this sentence, it is obvious that the person who opens the map is still Lan, so Vietnamese does not need to repeat Lan or cô ấy.

So this is natural:

• Lan không biết đường đến ngân hàng nên mở bản đồ trên điện thoại.

And this is also possible, but less economical:

• Lan không biết đường đến ngân hàng nên cô ấy mở bản đồ trên điện thoại.

Both are correct. The version without repetition sounds very natural.

Vietnamese verbs do not change form for tense the way English verbs do.

So mở can mean:

• opens
• opened
• will open

The time is usually understood from context, or it can be made explicit with time words or markers such as:

• đã = past
• đang = ongoing
• sẽ = future

For example:

• Lan đã mở bản đồ trên điện thoại. = Lan opened the map on her phone.
• Lan đang mở bản đồ trên điện thoại. = Lan is opening the map on her phone.
• Lan sẽ mở bản đồ trên điện thoại. = Lan will open the map on her phone.

Without a marker, the sentence is neutral and context decides the time.

No. Bản đồ is a fixed noun meaning map.

Here, bản is not functioning as a separate classifier that you can remove. It is part of the word itself. You cannot take đồ alone and have it mean map.

In fact:

• bản đồ = map
• đồ by itself usually means things, stuff, or objects

So learners should memorize bản đồ as one vocabulary item.

Both can work, but they mean slightly different things.

• mở bản đồ = open the map
• xem bản đồ = look at the map

On a phone, mở is very natural because you often first open an app or map. After that, you may look at it.

So this sentence focuses on the action of bringing the map up on the phone.

A similar English difference is:

• She opened the map on her phone
• She looked at the map on her phone

Both are possible, but they are not exactly the same action.

Yes. Here trên điện thoại means on the phone in the digital/device sense.

Vietnamese often uses trên for things displayed or used on a device:

• trên điện thoại = on the phone
• trên máy tính = on the computer
• trên màn hình = on the screen

It does not mean the map is physically sitting on top of the phone. It means the map is being accessed or shown on the phone.

Because Vietnamese often leaves possession unstated when it is obvious.

In English, you would usually say her phone. In Vietnamese, if context makes it clear that it is Lan’s phone, speakers often just say điện thoại.

So:

• mở bản đồ trên điện thoại naturally implies open the map on her phone

If you want to be explicit, you could say:

• mở bản đồ trên điện thoại của cô ấy = open the map on her phone

But that is not necessary here.

Vietnamese does not have articles like a, an, and the.

So nouns such as ngân hàng and điện thoại can mean:

• a bank / the bank
• a phone / the phone

The exact meaning depends on context.

If a speaker wants to make something more specific, Vietnamese uses other tools, such as demonstratives or extra description:

• ngân hàng đó = that bank
• điện thoại này = this phone
• điện thoại của Lan = Lan’s phone

So the lack of a/the is completely normal.

Often yes.

Both đến and tới can mean to or arrive at, and in many everyday sentences they are interchangeable.

So đường đến ngân hàng and đường tới ngân hàng are both understandable and natural.

That said, đến is a very standard and common choice, especially in neutral written Vietnamese.

Yes. It follows a very common pattern:

Subject + không + verb + object/complement + nên + verb phrase

In this sentence:

• Lan = subject
• không biết = does not know
• đường đến ngân hàng = the way to the bank
• nên = so / therefore
• mở bản đồ trên điện thoại = opens the map on the phone

So it is a useful model for making similar sentences, such as:

• Tôi không nhớ địa chỉ nên gọi bạn.
  I didn’t remember the address, so I called my friend.

• Nam bị mệt nên về nhà sớm.
  Nam was tired, so he went home early.