Hvis min bror sover her, finder vi en ekstra madras til ham.

Hvis means if and introduces a condition.

So Hvis min bror sover her means that the rest of the sentence only applies on that condition. In other words, if my brother sleeps here, then we’ll find an extra mattress for him.

A learner might compare hvis with når:

• hvis = if something happens
• når = when something happens

So this sentence presents sleeping here as a possibility, not as a certain event.

Danish often uses the present tense to talk about the future when the context makes the time clear.

Here, sover literally means sleeps, but in context it can mean is going to sleep or ends up sleeping here.

That is very normal in Danish:

• Hvis han kommer i morgen, laver vi kaffe.
• If he comes tomorrow, we make coffee / we’ll make coffee

English usually prefers will more often, but Danish does not need a separate future form here.

This is because Danish is a verb-second language in main clauses.

The first part of the sentence, Hvis min bror sover her, is a subordinate clause. When that whole clause comes first, it takes the first position in the sentence. Then the finite verb of the main clause must come next:

• Hvis min bror sover her, finder vi ...

So the order is:

1. fronted element: Hvis min bror sover her
2. finite verb: finder
3. subject: vi

If you start with the main clause instead, the order is normal:

• Vi finder en ekstra madras til ham, hvis min bror sover her.

The comma separates the subordinate clause from the main clause.

• Hvis min bror sover her = subordinate clause
• finder vi en ekstra madras til ham = main clause

In Danish, commas are commonly used to mark this boundary. So the comma helps show where the if-clause ends and the main statement begins.

In Danish, possessive words such as min, din, hans, vores usually replace the indefinite article.

So you say:

• min bror = my brother
• min bog = my book

Not:

• en min bror
• den min bror

That is similar to English, where you say my brother, not a my brother.

Because ham is the object form, while han is the subject form.

• han = he
• ham = him

After the preposition til, Danish uses the object form:

• til ham = for him / to him

Compare:

• Han sover her. = He sleeps here.
• Vi finder en madras til ham. = We find a mattress for him.

So han would be wrong here.

Til ham shows who the extra mattress is intended for.

In this sentence, finde noget til nogen means find something for someone. So:

• Vi finder en ekstra madras til ham = We’ll find an extra mattress for him

This use of til is very common when something is being provided for someone’s use or benefit.

Because madras is a common-gender noun in Danish, so its singular indefinite article is en.

• en madras = a mattress

The adjective ekstra means extra and does not change form here. So:

• en ekstra madras = an extra mattress

A useful contrast:

• en ekstra stol = an extra chair
• et ekstra tæppe = an extra blanket

Here the article changes because tæppe is a neuter noun, but ekstra stays the same.

Literally, yes: sleeps here.

But in natural usage, it often means something slightly broader, like:

• stays the night here
• sleeps over here
• spends the night here

So the sentence is probably not just about sleep in a physical sense. It usually means that if the brother is staying overnight, then they will arrange an extra mattress for him.

Yes. That version is completely natural and means essentially the same thing.

The difference is mainly one of focus and structure:

• Hvis min bror sover her, finder vi en ekstra madras til ham puts the condition first
• Vi finder en ekstra madras til ham, hvis min bror sover her starts with the result and adds the condition afterward

Also notice the word order difference:

• after initial Hvis..., you get finder vi
• when the main clause starts first, you get Vi finder

Yes, that is a very normal position.

Her means here and functions as an adverb of place. In a clause like min bror sover her, putting her at the end is very natural:

• subject: min bror
• verb: sover
• place adverbial: her

So the clause structure is straightforward:

• min bror = subject
• sover = verb
• her = place

That is similar to English my brother sleeps here.

In this context, it most naturally sounds like a real, practical condition: if that happens, we’ll do this.

So it is not mainly a habitual sentence like Whenever my brother sleeps here, we find an extra mattress for him, although Danish hvis can sometimes be interpreted more broadly depending on context.

Without extra context, the sentence sounds like a simple present/future condition about a possible situation.