Hun tager sine sandaler af ved døren, fordi de blev våde i regnen.

Because sine is the reflexive possessive form, used when the owner is the same as the subject of the clause.

• Hun tager sine sandaler af = she takes off her own sandals.
• Hun tager hendes sandaler af would usually mean she takes off another woman’s sandals.

Here, the subject is Hun, and the sandals belong to her, so sine is correct.

Also, sine is used because sandaler is plural. The reflexive possessive forms are:

• sin for common gender singular
• sit for neuter singular
• sine for plural

In Danish, when you use a possessive word like min, din, hans, hendes, sin, vores and so on, you do not also use an article.

So:

• sine sandaler = her sandals

Not:

• de sine sandaler

This works much like English: we say her sandals, not the her sandals.

Because tage af is a verb expression meaning take off, and in Danish the particle af is often separated from the finite verb in a main clause.

So:

• Hun tager sine sandaler af

This is very normal Danish word order.

You can think of it like this:

• tager = the finite verb, which comes early in the sentence
• af = the particle, which comes later

This is similar to English take off:

• She takes her sandals off

With an object in the sentence, the particle often comes after the object.

No, that would not be correct here.

With tage ... af meaning take off, the usual pattern is:

• tage + object + af

So:

• Hun tager sine sandaler af
• Hun tager dem af

That is the normal structure.

Ved here means by, at, or near the door.

So ved døren means she takes them off in the area of the door, probably as she comes inside.

Compare:

• ved døren = by the door / at the door
• i døren = in the door, which would sound strange here
• til døren = to the door, showing movement toward it

Since this sentence describes the location where she takes them off, ved is the natural choice.

Because fordi introduces a subordinate clause, and subordinate clauses in Danish usually have a different word order from main clauses.

In a main clause, Danish normally has verb-second order:

• De blev våde

But after fordi, the subject comes before the finite verb:

• fordi de blev våde

So the clause order is normal subordinate-clause order.

De refers to sandaler.

Since sandaler is plural, the pronoun must also be plural:

• sandaler → de

So the sentence means that the sandals got wet, not the woman.

Blev våde means became wet or got wet, so it focuses on the change of state.

• de blev våde i regnen = they got wet in the rain

If you said de var våde, that would simply describe their state:

• they were wet

So blev is more natural if the idea is that the rain caused them to become wet.

Because the adjective agrees with a plural noun or pronoun.

Here, de refers to the plural noun sandaler, so the adjective is plural too:

• singular common gender: våd
• singular neuter: vådt
• plural: våde

So:

• En sandal blev våd = one sandal got wet
• Sandalerne blev våde = the sandals got wet

I regnen means in the rain, and it is a very natural Danish expression for something happening while exposed to rain.

So:

• de blev våde i regnen = they got wet in the rain

English speakers sometimes expect something like from the rain, but Danish often uses i regnen to describe the situation or environment.

The sentence mixes a present action with a past cause:

• Hun tager sine sandaler af = she takes off her sandals
• fordi de blev våde i regnen = because they got wet in the rain

This makes sense if she is taking them off now because they became wet earlier.

Danish does this naturally. If you wanted the whole sentence in the past, you could say:

• Hun tog sine sandaler af ved døren, fordi de blev våde i regnen.

Because fordi introduces a subordinate clause, and Danish normally places a comma between the main clause and the subordinate clause.

So:

• Hun tager sine sandaler af ved døren, fordi de blev våde i regnen.

That comma is standard Danish punctuation.

For a sentence like this, yes, fordi is the normal word.

• fordi = because

There are other Danish words that can relate to cause, such as da in some contexts, but fordi is the straightforward, everyday choice when you are giving a reason.

So in this sentence, fordi is exactly what you would expect.