Der Polizist hilft dem Kind.

Because helfen takes the dative case in German.

So in this sentence:

• der Polizist = the subject, so it is in the nominative
• dem Kind = the person receiving the help, so it is in the dative

German says:

• jemand hilft einem Kind = someone helps a child

So das Kind would be nominative or accusative, but after helfen, German uses dem Kind.

Der Polizist is in the nominative case because it is the subject of the sentence — the one doing the action.

A quick breakdown:

• der Polizist = the police officer is helping
• hilft = helps
• dem Kind = the child receives the help

So the structure is:

• subject (nominative)
  • verb
    • dative object

Because der Polizist is the subject, not the object.

In German:

• der Polizist = nominative singular
• den Polizisten = accusative singular
• dem Polizisten = dative singular

Since the police officer is the one doing the helping, nominative is needed, so der Polizist is correct.

Also, Polizist is a type of noun that often adds -en in cases other than nominative singular, which is why you may later see forms like:

• des Polizisten
• dem Polizisten
• den Polizisten

But here, nominative singular is simply der Polizist.

Hilft is the 3rd person singular present tense form of helfen.

The verb helfen means to help.

Its present-tense forms are:

• ich helfe = I help
• du hilfst = you help
• er/sie/es hilft = he/she/it helps
• wir helfen = we help
• ihr helft = you all help
• sie/Sie helfen = they/you help

Since der Polizist is he in grammatical terms, the sentence uses hilft.

This is simply a property of the verb helfen. Some German verbs require a specific case, and helfen requires the dative.

So German says:

• Ich helfe dem Mann.
• Sie hilft der Frau.
• Wir helfen dem Kind.

This is different from English, where help just takes a normal object without visible case marking.

For learners, it is best to memorize helfen + dative as a set pattern.

Yes, German word order is somewhat flexible, as long as the finite verb stays in the second position in a main clause.

So these are possible:

• Der Polizist hilft dem Kind.
• Dem Kind hilft der Polizist.

Both mean roughly the same thing: The police officer helps the child.

The difference is mainly emphasis:

• Der Polizist hilft dem Kind. = neutral
• Dem Kind hilft der Polizist. = puts more focus on the child

Because the case endings show who is doing what, German can move parts around more easily than English.

You know from the case markings, not just from word order.

In this sentence:

• der Polizist = nominative = the helper
• dem Kind = dative = the one being helped

So even if you changed the order to Dem Kind hilft der Polizist, the meaning would still be the same, because the articles show the roles clearly.

This is an important feature of German: articles often tell you the job of the noun in the sentence.

Because in German, all nouns are capitalized.

So:

• der Polizist
• das Kind
• die Frau
• das Haus

This is a standard spelling rule in German, not something special about this sentence.

Dem is the dative singular definite article for:

• masculine nouns
• neuter nouns

Since Kind is a neuter noun (das Kind), its dative singular form is:

• nominative: das Kind
• dative: dem Kind

So dem tells you two things at once:

1. the noun is in the dative
2. the noun is singular and here neuter

It is singular.

• das Kind = the child
• die Kinder = the children

In the sentence dem Kind, the article dem and the noun form Kind both show that it is singular.

If it were plural, you would normally get something like:

• den Kindern = the children, in the dative plural

So Der Polizist hilft dem Kind means The police officer helps the child, not the children.