Wij dienen het bezwaarschrift in.

Because the full verb is indienen, which is a separable verb in Dutch.

In a normal main clause, Dutch often splits this kind of verb:

• Wij dienen het bezwaarschrift in.

Here:

• dienen = the conjugated part
• in = the separable prefix, moved to the end

Compare:

• infinitive: indienen
• main clause: Wij dienen ... in
• past participle: ingediend

Examples:

• Wij willen het bezwaarschrift indienen.
• Wij hebben het bezwaarschrift ingediend.

So in is not a separate preposition here; it belongs to the verb indienen.

Not by itself in this sentence. On its own, dienen can mean to serve or to be useful, but here it is part of the separable verb indienen.

So:

• dienen = can mean serve
• indienen = submit, file, hand in

That is why you should understand the sentence as using indienen, not plain dienen.

Bezwaarschrift is a formal, legal or administrative word. It means a written objection, often something like a formal letter or document in which you object to a decision.

It is a compound noun:

• bezwaar = objection
• schrift = writing/document

So het bezwaarschrift is the formal written objection.

In everyday English, the best translation depends on context:

• objection letter
• notice of objection
• written objection
• sometimes appeal, though that can be slightly different legally

Because bezwaarschrift is a het-word in Dutch.

Dutch nouns take either:

• de
• or het

This noun is:

• het bezwaarschrift

You simply have to learn the article with the noun. A useful habit is to memorize nouns as:

• het bezwaarschrift not just
• bezwaarschrift

Both wij and we can mean we.

• we is more common in everyday speech
• wij is a bit more careful, emphatic, or formal

So these are both possible:

• Wij dienen het bezwaarschrift in.
• We dienen het bezwaarschrift in.

In a formal or written context, especially with a word like bezwaarschrift, wij fits very naturally.

Yes. This is standard Dutch main-clause word order.

Structure:

• Wij = subject
• dienen = finite verb in second position
• het bezwaarschrift = object
• in = separable prefix at the end

So the pattern is:

• Subject + finite verb + object + separable prefix

This is very common with separable verbs:

• Ik vul het formulier in.
• Zij zegt de afspraak af.
• Wij dienen het bezwaarschrift in.

Then the separable verb usually stays together in the infinitive.

For example:

• Wij willen het bezwaarschrift indienen.
• Wij moeten het bezwaarschrift indienen.

Here you do not split it:

• indienen

The split mainly happens when the verb is the finite verb in a main clause:

• Wij dienen het bezwaarschrift in.

You usually put niet before the final separable prefix, or after the object if the object is definite, as it is here.

So:

• Wij dienen het bezwaarschrift niet in.

This means:

• We are not submitting the written objection.

The separable prefix in still stays at the end.

In a yes/no question, Dutch usually puts the finite verb first:

• Dienen wij het bezwaarschrift in?

The separable prefix still stays at the end.

If you use we, you can also say:

• Dienen we het bezwaarschrift in?

Yes, it sounds fairly formal, mainly because of:

• bezwaarschrift — a legal/administrative term
• wij — slightly more formal than we
• indienen — common in official contexts for submit/file

So this is exactly the kind of sentence you might see or hear in government, legal, tax, or administrative situations.