Han spiser en skive brød med syltetøj, når han ikke har tid til at lave mere mad.

En skive brød is a very common Danish way to say a slice of bread.

• skive = slice
• brød = bread

In this kind of expression, Danish often uses a measure/container word + noun without af:

• en skive brød = a slice of bread
• et glas vand = a glass of water
• en kop kaffe = a cup of coffee

So brød is functioning like a material or mass noun here, not as a separate countable item. That is why there is no article before brød.

Yes, but the meaning is a little different.

• en skive brød = a slice of bread
  This suggests a normal cut slice, like from a loaf.
• et stykke brød = a piece of bread
  This is more general and less specific about shape.

In this sentence, en skive brød sounds more natural because it matches the idea of bread with jam on it.

Because med syltetøj means the jam is on / with the bread, not a separate item.

• brød med syltetøj = bread with jam
• brød og syltetøj = bread and jam

Using og would sound more like two separate things being listed. Using med shows that the jam goes together with the bread as a topping or accompaniment.

Here når is used because the sentence describes something that happens regularly or typically.

• når = when, whenever
• hvis = if

So:

• Han spiser ... når han ikke har tid ...
  = He eats ... when/whenever he does not have time ...

This suggests a usual pattern or habit.

If you said hvis han ikke har tid, it would sound more like a possible condition: if he doesn’t have time.

Because Danish often uses the present tense for habitual actions or general truths, just like English does.

So Han spiser en skive brød med syltetøj does not have to mean he is eating it right now. It can mean:

• he eats it
• he usually eats it
• that is what he does in that situation

The clause with når helps show that this is a repeated or typical action.

Because Danish word order changes in subordinate clauses.

After a subordinating word like når, at, fordi, hvis, the usual pattern is:

subject + sentence adverb + verb

So:

• når han ikke har tid = when he does not have time

Here:

• han = subject
• ikke = sentence adverb
• har = finite verb

In a main clause, Danish often places ikke after the finite verb:

• Han har ikke tid.

But in this subordinate clause, ikke comes before har.

Because Danish normally uses the pattern:

have tid til at + infinitive

This means to have time to do something.

So:

• han har tid til at lave mad = he has time to make food

You should learn this as a common structure:

• have lyst til at ... = feel like doing ...
• have brug for at ... = need to ...
• have tid til at ... = have time to ...

The til is required here; you cannot just say har tid at lave.

Yes, lave mad is a very common everyday expression meaning to make food / cook.

• lave = make, do
• mad = food

So at lave mad often means to cook in a general, ordinary sense.

Other verbs are possible, but they are different in tone or meaning:

• at lave mad = everyday, natural, general
• at tilberede mad = to prepare food, more formal
• at koge = to boil
• at stege = to fry/roast

In this sentence, lave mad is the most natural choice.

Here mere means more / additional.

So at lave mere mad means:

• to make more food
• to prepare something more substantial
• to make additional food than just the slice of bread

It suggests that the slice of bread with jam is a quick option instead of preparing something else.

Usually it means he doesn’t have the time for making more food in that situation. In practice, that often means not enough time, not necessarily zero time in an absolute sense.

So the sentence is understood naturally as:

• when he is too busy to prepare anything more elaborate

That is often how ikke have tid til works in real usage.

Yes, it is natural. Brød med syltetøj is perfectly understandable and idiomatic.

That said, in everyday speech a Dane might also say:

• en skive med syltetøj
• en skive rugbrød med syltetøj
• en mad med syltetøj in some contexts

But the sentence you have is completely normal and clear.

In Danish, a comma before a subordinate clause is common and standard, and this sentence does include it:

Han spiser en skive brød med syltetøj, når han ikke har tid til at lave mere mad.

So the comma is marking the start of the subordinate clause introduced by når.

This is very normal in written Danish.