Learn Hardcore Swedish: På natten har han ofta en dröm som han inte vill berätta om. - At night he often has a dream that he does not want to talk about.

I natten is usually not used in standard Swedish in this meaning.
Om natten does exist, but sounds old‑fashioned or literary. In everyday speech, på natten is the default for “at night” when talking about a general, repeated situation.

So På natten har han ofta en dröm … = “At night he often has a dream …” (in general, on nights).

Why does the verb come right after På natten? Why not På natten han har ofta …?

Swedish has the V2 rule (Verb Second): in a main clause, the finite verb (here: har) must be in second position in the sentence.

Word order here:

På natten – first element (adverbial of time)
har – finite verb (must be in position 2)
han – subject
ofta en dröm som han inte vill berätta om – the rest

You could also say:

Han har ofta en dröm på natten …

Here the subject (han) is first, the verb (har) is still second.
What you cannot do is break the V2 rule:

❌ På natten han har ofta en dröm … (wrong in standard Swedish)
✅ På natten har han ofta en dröm …

Why is it har en dröm and not just drömmer?

Both are possible, but they sound a bit different:

Han har ofta en dröm – literally “He often has a dream.”
Han drömmer ofta – “He often dreams.”

Har en dröm:

Feels a little more concrete or specific: there is a particular dream.
Fits well with adding a relative clause som han inte vill berätta om (“that he doesn’t want to talk about”).

Drömmer:

Focuses more on the activity of dreaming in general.
You could say På natten drömmer han ofta om något som han inte vill berätta om, but that changes the structure a bit.

So har en dröm highlights a particular dream that can then be described with som ….

Why is the adverb ofta in the middle: har han ofta en dröm and not har ofta han en dröm?

In Swedish main clauses, most sentence adverbs (like ofta, inte, alltid, kanske) usually come:

after the finite verb
before the subject if the subject is not in first position, or
after the subject if the subject is in first position

In this sentence, the first position is På natten, then the verb har, then the subject han. Where does ofta go? After the subject:

På natten har han ofta en dröm …

Other common patterns:

Han har ofta en dröm. (Subject first: adverb after subject)
Ibland har han en dröm. (“Ibland” is first: verb second, subject third)

Har ofta han en dröm is not normal word order in Swedish.

What does som do in en dröm som han inte vill berätta om?

Som is a relative pronoun, like that/which/who in English.

en dröm som han inte vill berätta om
= a dream that he does not want to talk about

Here’s the structure:

en dröm – the noun being described
som – introduces a relative clause referring back to dröm
han inte vill berätta om – relative clause describing the dream

So som links dröm with the extra information about it.

Why is the preposition om at the end: berätta om? Can you say … som han inte vill berätta det instead?

Some important points:

berätta om (något) means “to tell about (something) / talk about (something)”.
In the sentence, om is part of the verb phrase berätta om.
Swedish allows the preposition to stay at the end of the clause, especially after a relative pronoun like som.

So:

en dröm som han inte vill berätta om
literally: “a dream that he does not want to tell about”

You cannot just replace it with a direct object pronoun:

❌ som han inte vill berätta det – wrong
✅ som han inte vill berätta om – correct
✅ som han inte vill berätta om för någon – “that he doesn’t want to tell anyone about”

If you want to include a pronoun, it usually appears after om:

Han vill inte berätta om den. – “He doesn’t want to talk about it.”

Why is negation inte before vill and not after, like han vill inte berätta om?

In this clause we have:

modal verb: vill (want to)
main verb: berätta (tell)

The normal order in a simple clause is:

subject – finite verb – inte – rest

So:

han vill inte berätta om det – “he does not want to talk about it”

But in the relative clause we have V2 again:

(som) han inte vill berätta om

Here, som is first, han ends up in the “subject slot”, vill is the finite verb that must be second element in that clause, and inte comes after the subject but before the finite verb in this particular kind of embedded clause. Many learners simply memorize this whole chunk som han inte vill … as a pattern.

Both patterns are useful to know:

Main clause: Han vill inte berätta om det.
Relative clause: … som han inte vill berätta om.

Why is it en dröm and not ett dröm?

Every Swedish noun has a grammatical gender:

en-words (common gender)
ett-words (neuter)

The word dröm is an en-word, so it takes:

en dröm – a dream
drömmen – the dream
drömmar – dreams
drömmarna – the dreams

You just have to memorize the gender with each noun. There is no rule that predicts it for dröm; dictionaries usually mark it as en dröm.

Does På natten mean “tonight” or “at night in general”?

På natten here means “at night (in general / usually)”, a general, recurring time:

På natten har han ofta en dröm …
= On (the) nights, he often has a dream …

For tonight, Swedish normally uses:

i natt – tonight / last night (depending on context)

So:

I natt hade han en konstig dröm. – Tonight / last night he had a strange dream.
På natten har han ofta konstiga drömmar. – At night he often has strange dreams. (habitual)

What is the difference between På natten and På nätterna?

På natten – literally “on the night”, but used to mean “at night (in general)” as a time of day.
På nätterna – “on the nights”, more clearly “at nights / during nights (plural)”, often with a stronger sense of repeated nights.

Examples:

På natten är det mörkt. – It is dark at night. (general statement)
På nätterna sover han dåligt. – He sleeps badly at nights. (emphasizes repeated nights)

In your sentence, På natten har han ofta en dröm …, På natten already suggests a repeated situation, so På nätterna would be possible but a bit heavier and more explicitly plural.

Could you say en dröm som han inte vill tala om instead of berätta om?

Yes, you could:

en dröm som han inte vill berätta om
en dröm som han inte vill tala om

Both mean roughly “a dream that he doesn’t want to talk about”.

Nuance:

berätta om – “tell about”, often more like narrating / telling a story.
tala om – “speak about / talk about”, slightly more neutral.

In many everyday contexts they overlap. In this sentence, berätta om fits very naturally because we are imagining someone describing a dream as a story.