Når appelsinerne er modne, skræller jeg dem ikke så forsigtigt.

Når means when in the sense of a general or repeated situation.

So Når appelsinerne er modne means something like:

• whenever the oranges are ripe
• when the oranges are ripe

A native English speaker might wonder whether this refers to one specific moment or a general rule. In Danish, når is commonly used for:

• general truths
• repeated situations
• things that happen whenever a condition is met

If you were talking about one specific past occasion, Danish would often use da instead.

Appelsinerne is the definite plural form, meaning the oranges.

Here is the pattern:

• en appelsin = an orange
• appelsinen = the orange
• appelsiner = oranges
• appelsinerne = the oranges

Danish often attaches definiteness to the end of the noun instead of using a separate word like the.

So:

• appelsinerne = the oranges
• not just oranges in general

Because modne is an adjective agreeing with a plural noun.

The basic adjective is:

• moden = ripe

But when used about plural nouns, it becomes:

• modne = ripe, plural form

So:

• appelsinen er moden = the orange is ripe
• appelsinerne er modne = the oranges are ripe

This is a very common pattern in Danish adjective agreement.

Also, here the adjective is predicative, meaning it comes after er rather than directly before the noun.

This is because Danish follows the V2 rule in main clauses: the finite verb must come in the second position.

The first part of the sentence is the subordinate clause:

• Når appelsinerne er modne

After that, the main clause starts. Since something else has already been placed first, the verb must come before the subject:

• skræller jeg dem ikke så forsigtigt

So the structure is:

1. first element: Når appelsinerne er modne
2. finite verb: skræller
3. subject: jeg

If the sentence began directly with the subject, it would be:

• Jeg skræller dem ikke så forsigtigt, når appelsinerne er modne.

That is why jeg moves after the verb in your original sentence.

Dem is the object pronoun meaning them.

It refers back to appelsinerne.

So the pattern is:

• jeg skræller appelsinerne = I peel the oranges
• jeg skræller dem = I peel them

In Danish:

• de is usually the subject form = they
• dem is the object form = them

So here dem is correct because it is the thing being peeled.

In Danish, ikke normally comes before the thing it negates.

Here it negates the degree phrase så forsigtigt:

• ikke så forsigtigt = not so carefully / not that carefully

So the sentence is not saying that peeling does not happen. It says that the peeling is done with less care.

Compare:

• Jeg skræller dem ikke. = I do not peel them.
• Jeg skræller dem ikke forsigtigt. = I do not peel them carefully.
• Jeg skræller dem ikke så forsigtigt. = I do not peel them so carefully / not that carefully.

That placement is very natural in Danish.

Here så means something like so, that, or to that degree.

So:

• forsigtigt = carefully
• så forsigtigt = so carefully / that carefully
• ikke så forsigtigt = not so carefully / not that carefully

This often suggests a comparison, either explicit or implied.

For example, it can imply:

• not as carefully as before
• not as carefully as one might expect
• not all that carefully

English sometimes prefers not very carefully in natural speech, but Danish ikke så forsigtigt is perfectly normal and often has that kind of nuance.

Because forsigtigt is an adverb here, and it comes from the adjective forsigtig.

• forsigtig = careful
• forsigtigt = carefully

A lot of Danish adverbs are formed by adding -t to the adjective.

Examples:

• hurtig = quick

• hurtigt = quickly

• forsigtig = careful
• forsigtigt = carefully

So in this sentence, forsigtigt describes how the peeling is done.

Yes. Skræller is the present tense of skrælle, meaning to peel.

• at skrælle = to peel
• jeg skræller = I peel / I am peeling

In this sentence, because of når, the present tense often has a habitual or general sense:

• whenever the oranges are ripe, I peel them not so carefully

So it does not have to mean one single action happening right now. It can describe a regular pattern.

Because Når appelsinerne er modne is a subordinate clause placed before the main clause.

Danish punctuation normally separates that clause from the main clause with a comma:

• Når appelsinerne er modne, skræller jeg dem ikke så forsigtigt.

This is very standard and helps show the structure clearly:

• subordinate clause first
• then main clause

Yes. A very common alternative is:

• Jeg skræller dem ikke så forsigtigt, når appelsinerne er modne.

Both are grammatical.

The difference is mainly about focus:

• Når appelsinerne er modne, skræller jeg dem ikke så forsigtigt.
  This puts the time/condition first.

• Jeg skræller dem ikke så forsigtigt, når appelsinerne er modne.
  This starts with I peel them..., so the action gets the first spotlight.

Because Danish uses the V2 rule, moving the subordinate clause to the front changes the order in the main clause from jeg skræller to skræller jeg.