Det ser ut til at barna ikke vil ha sitron i vannet, så de vil heller ha saft.

Det ser ut til at means it looks like or it seems that.

It is a very common Norwegian pattern:

• det = it
• ser ut = looks / appears
• til at = introduces the clause that follows

So Det ser ut til at barna ... means It looks like the children ...

You should learn ser ut til at as a fixed expression. It often works like English it seems that.

Here det is a dummy subject, just like English it in:

• It seems that...
• It is raining
• It is important to learn this

The det does not point to a concrete thing. It is simply required by the grammar of the sentence.

So in Det ser ut til at ..., det is grammatical, not meaningful in a concrete way.

Barna is the definite plural form of barn.

The forms are:

• et barn = a child
• barnet = the child
• barn = children
• barna = the children

So barna means the children, not just children in general.

This is because the part after at is a subordinate clause, and subordinate clauses in Norwegian usually have different word order from main clauses.

Compare:

• Barna vil ikke ha sitron i vannet.
  Main clause: the children do not want lemon in the water.

• ... at barna ikke vil ha sitron i vannet.
  Subordinate clause: ... that the children do not want lemon in the water.

In a main clause, ikke usually comes after the finite verb:

• vil ikke

In a subordinate clause, ikke usually comes before the finite verb:

• ikke vil

This is one of the most important word-order patterns in Norwegian.

Because vil is a modal verb, and modal verbs in Norwegian are normally followed by the infinitive without å.

Examples:

• jeg vil spise = I want to eat
• hun kan komme = she can come
• de må gå = they must go
• barna vil ha saft = the children want to have / want

So vil ha is correct, and vil å ha is not.

Literally, ha means have, but in Norwegian it is often used where English would say want in food and drink contexts.

So:

• ha sitron i vannet = have lemon in the water
• ha saft = have some squash/cordial/juice drink

In context, vil ha often translates naturally as:

• want
• would like

So de vil heller ha saft is naturally they would rather have saft or they want saft instead.

Because both are being used more like uncountable substances here, not as single countable items.

• sitron i vannet = lemon in the water
• ha saft = have saft / some fruit drink

This is similar to English, where we often say:

• They don’t want lemon in the water
• They want juice instead

We do not have to say a lemon or a saft.

If you wanted to talk about one whole lemon, you could say en sitron.

Vannet is the definite form of vann:

• vann = water
• vannet = the water

So i vannet means in the water.

In context, this usually means a specific water already understood from the situation, such as the water they are drinking. Norwegian often uses the definite form where English may be a bit looser and just say water.

So sitron i vannet is very natural for lemon in the water.

Here heller means rather or instead.

So:

• de vil heller ha saft = they would rather have saft / they want saft instead

It shows preference between two options:

• not lemon in the water
• but saft instead

A useful contrast:

• heller = rather / instead
• ikke heller = not either / neither

Example:

• Jeg vil heller ha te. = I’d rather have tea.
• Jeg vil ikke ha kaffe heller. = I don’t want coffee either.

No, Norwegian normally needs an explicit subject in a full clause.

So after så, you need something like:

• så de vil heller ha saft
• så barna vil heller ha saft

Here de refers back to barna.

Using de avoids repeating barna, and that sounds natural. Repeating barna would also be grammatical, but a little heavier.

Because så here means so, and it is acting as a coordinating conjunction joining two main clauses.

After a coordinating conjunction like this, the next clause usually keeps normal main-clause word order:

• så de vil heller ha saft

That is similar to English:

• ..., so they would rather have saft

If så were being used more like then, especially at the start of a sentence, you could get inversion:

• Så vil de heller ha saft.

But in your sentence, så means so, so så de vil ... is the expected structure.

Saft is not exactly the same as English juice.

In Norwegian, saft usually means a sweet fruit drink, often made from concentrate and mixed with water. Depending on context, English translations might be:

• juice
• cordial
• squash
• fruit drink

So the exact English word depends on the variety of English and the situation. But the important point is that it is a sweet drink, often given to children.

Yes, you could, but there is a slight difference in emphasis.

• sitron i vannet = lemon in the water
  This focuses on the lemon being added to the water.

• sitronvann = lemon water
  This treats it more as the name of the drink.

So the original sentence emphasizes what is in the water, while sitronvann would sound a bit more like naming the drink itself.

Both are natural, but they are not always identical in nuance.

Yes. That would be a more direct statement:

• Barna vil ikke ha sitron i vannet. = The children do not want lemon in the water.

But Det ser ut til at barna ikke vil ha ... is softer and less direct. It means something like:

• It looks like the children don’t want ...
• It seems that the children don’t want ...

So the original sentence suggests the speaker is drawing a conclusion from what they see or observe, rather than stating it as a plain fact.