Η δημοτική αστυνομία ελέγχει τον κωδικό παράβασης.

Because adjectives in Greek agree with the noun they describe in gender, number, and case.

Here, αστυνομία is:

• feminine
• singular
• nominative

So the adjective must also be feminine singular nominative:

• δημοτικός = masculine
• δημοτική = feminine
• δημοτικό = neuter

So η δημοτική αστυνομία means the municipal police.

In Greek, αστυνομία is a singular feminine noun referring to the police as an institution or force. That is why the verb is also singular:

• Η αστυνομία ελέγχει = The police checks/is checking

English and Greek simply handle this idea differently. English usually says the police are, but Greek says η αστυνομία είναι / ελέγχει, with a singular verb.

Yes, Greek uses the definite article very often. In this sentence, η means the and goes with the whole noun phrase δημοτική αστυνομία.

Greek frequently uses the article with:

• specific nouns
• institutions
• subjects of sentences

Also, Greek has no separate word for a/an. So learners often notice that articles work a bit differently from English.

Because it is in the nominative case, which is the normal case for the subject.

You can see this from the forms:

• η δημοτική αστυνομία = nominative
• τον κωδικό = accusative

So the sentence structure is:

• subject: η δημοτική αστυνομία
• verb: ελέγχει
• object: τον κωδικό παράβασης

Greek often shows who is doing what through case endings, not only through word order.

Because κωδικό is the direct object of the verb ελέγχει, so it must be in the accusative case.

Compare:

• ο κωδικός = nominative, the code as subject
• τον κωδικό = accusative, the code as object

So:

• Ο κωδικός είναι σωστός. = The code is correct.
• Ελέγχει τον κωδικό. = He/She/It checks the code.

παράβασης is genitive singular of παράβαση.

The genitive often means of ..., so:

• κωδικός παράβασης = code of violation/offense
• more naturally in English: violation code or offense code

So παράβασης is modifying κωδικό and telling you what kind of code it is.

Because here παράβασης is being used as a genitive modifier, almost like part of a fixed label or category: violation code.

So:

• τον κωδικό παράβασης = the violation code / the offense code

If you said:

• τον κωδικό της παράβασης

that would sound more like:

• the code of the violation
• meaning a more specific, already identified violation

So the version without the article is more natural when talking about the type or category.

Here are the basic forms:

• η → the feminine singular definite article
• δημοτική → dictionary form δημοτικός = municipal
• αστυνομία → police
• ελέγχει → dictionary form ελέγχω = I check / inspect / verify
• τον → masculine singular accusative definite article
• κωδικό → dictionary form κωδικός = code
• παράβασης → dictionary form παράβαση = violation, offense, infringement

No. ελέγχω can have several related meanings depending on context, such as:

• check
• inspect
• verify
• audit
• sometimes control or monitor

In this sentence, checks or verifies is the most natural translation.

Yes. Greek word order is more flexible than English because the cases help show the grammatical roles.

The neutral order here is:

• Η δημοτική αστυνομία ελέγχει τον κωδικό παράβασης.

But you could also say:

• Τον κωδικό παράβασης ελέγχει η δημοτική αστυνομία.

That still means the same basic thing, but it puts more emphasis on τον κωδικό παράβασης.

Usually it means the institution/service as a whole, not one individual person.

So in this sentence, a Greek speaker would normally understand:

• the municipal police as an authority or department

If you wanted to talk about a specific officer, you would normally use something like:

• ο δημοτικός αστυνομικός = the municipal police officer