Børnene elsker sådan nogle kiks, når vi sidder i haven om eftermiddagen.

In Danish, the definite article is usually attached to the end of the noun instead of being a separate word.

• et barn = a child
• børn = children
• børnene = the children

So -ene here is the definite plural ending. English uses a separate word (the children), but Danish often builds that meaning into the noun itself.

Because barn is an irregular noun.

Its forms are:

• et barn = a child
• barnet = the child
• børn = children
• børnene = the children

So this is just one of those noun patterns you need to learn as a set.

Elsker is the present tense form of the verb at elske (to love).

• at elske = to love
• elsker = love / loves

Danish verbs do not change for person the way English verbs do. So:

• jeg elsker = I love
• du elsker = you love
• vi elsker = we love
• børnene elsker = the children love

The same present-tense form works for all subjects.

Sådan nogle kiks means something like:

• biscuits/cookies like that
• that kind of biscuit/cookie
• those sorts of biscuits/cookies

The phrase is a very natural spoken Danish way to refer to a type of thing without naming it very precisely.

• sådan = such / like that
• nogle = some

Together, sådan nogle + plural noun often means things of that kind.

They work together to create a natural idiomatic phrase.

• nogle kiks = some biscuits/cookies
• sådan nogle kiks = biscuits/cookies like that, that sort of biscuits/cookies

So nogle gives the idea of an indefinite plural, and sådan adds the idea of that kind/type. English often uses a whole phrase for this, while Danish commonly uses sådan nogle.

Yes, but it sounds more formal or written.

• sådan nogle kiks = common, natural, conversational
• sådanne kiks = more formal, more written-style

A learner will hear sådan nogle much more often in everyday speech.

Here når means when or whenever.

In this sentence it suggests a repeated or typical situation:

• Børnene elsker sådan nogle kiks, når vi sidder i haven om eftermiddagen.
• The children love that kind of biscuit when/whenever we sit in the garden in the afternoon.

This is not really an if sentence. It describes something that generally happens.

A useful contrast:

• når = when / whenever
• hvis = if

So når is the right choice here.

Most likely it describes a habit or a typical situation.

That comes from the combination of:

• present tense (elsker, sidder)
• når
• om eftermiddagen

Together they sound like whenever we sit in the garden in the afternoon or when we sit in the garden in the afternoons, not just one single event.

Danish often prefers a position verb where English might simply use be.

So:

• vi sidder i haven = literally we sit in the garden
• but in natural English, this may simply mean we’re in the garden, sitting there

This is very common in Danish:

• sidde = sit
• stå = stand
• ligge = lie
• hænge = hang

Danish often pays attention to the physical position of people and things more than English does.

For the same reason as børnene: Danish usually adds the definite article as an ending.

• en have = a garden
• haven = the garden

So i haven literally means in the-garden, but in normal English we just say in the garden.

Because i is the normal preposition for being in an enclosed or defined space such as a garden, room, house, box, etc.

• i haven = in the garden
• i huset = in the house
• i køkkenet = in the kitchen

På is used in other kinds of expressions, but not here.

Om eftermiddagen means in the afternoon or in the afternoons.

This is a standard Danish time expression:

• om morgenen = in the morning
• om formiddagen = in the late morning
• om eftermiddagen = in the afternoon
• om aftenen = in the evening

With om + part of day + definite form, Danish often expresses something habitual or general.

Compare:

• i eftermiddag = this afternoon
• om eftermiddagen = in the afternoon / in the afternoons

So om eftermiddagen fits the habitual meaning of the sentence very well.

Because in this type of time expression, Danish normally uses the definite form.

• eftermiddag = afternoon
• eftermiddagen = the afternoon

But the whole phrase om eftermiddagen is best learned as a set expression meaning in the afternoon / in the afternoons. It does not sound as specifically definite in English as it looks in Danish.

Yes. Når introduces a subordinate clause, and the normal order is:

når + subject + verb

So:

• når vi sidder i haven ...
• not når sidder vi ...

That is very normal Danish subordinate-clause word order.

If the når clause came first, then the main clause would show inversion:

• Når vi sidder i haven om eftermiddagen, elsker børnene sådan nogle kiks.

That is another very useful Danish pattern to recognize.

It depends a little on context. Kiks can cover several kinds of dry baked snacks.

In this sentence, because it is something the children love in the afternoon, English might naturally translate it as:

• biscuits in British English
• cookies or sometimes crackers in American English, depending on the exact kind

So the exact English word depends on what sort of kiks is meant. The Danish word itself is a bit broader than a single fixed English equivalent.