Der Notruf erreicht die Polizei während des Einbruchs.

In this sentence, der Notruf is the subject and die Polizei is the direct object.

You can tell because of the articles:

• der Notruf = nominative masculine singular
• die Polizei = accusative feminine singular

So the structure is:

• Der Notruf = the emergency call
• erreicht = reaches
• die Polizei = the police

A very literal breakdown is:

• The emergency call reaches the police

This is one of the big advantages of German case marking: even if the word order changes, the article often shows you what role the noun is playing.

Because the verb is conjugated for third person singular.

The infinitive is erreichen = to reach.

Present tense:

• ich erreiche
• du erreichst
• er/sie/es erreicht
• wir erreichen
• ihr erreicht
• sie/Sie erreichen

Since der Notruf is singular, the verb must be erreicht.

Because während normally takes the genitive in standard German.

So:

• während
  • genitive
• der Einbruch becomes des Einbruchs in the genitive singular

That is why you get:

• während des Einbruchs = during the burglary

Forms of Einbruch:

• nominative: der Einbruch
• accusative: den Einbruch
• dative: dem Einbruch
• genitive: des Einbruchs

You may hear während dem Einbruch in some spoken varieties, but in standard written German, während des Einbruchs is the expected form.

That extra -s is a normal genitive ending for many masculine and neuter nouns in German.

Since Einbruch is masculine (der Einbruch), its genitive singular is:

• des Einbruchs

This is very common:

• der Mann → des Mannes / des Manns
• der Tag → des Tages
• der Einbruch → des Einbruchs

So there are really two changes:

1. der changes to des
2. Einbruch gets the genitive ending -s

In German, die Polizei is grammatically singular in this kind of sentence.

So German says:

• die Polizei ist da = the police are here / the police is here in literal grammar

Even though English uses a plural-looking expression, German treats Polizei here as a singular collective noun referring to the police force or the police as an institution.

That is why the object is:

• die Polizei not something plural like die Polizeien

Anruf is a general phone call.

Notruf specifically means an emergency call.

So:

• ein Anruf = a call
• ein Notruf = an emergency call, usually to emergency services

In this sentence, der Notruf erreicht die Polizei suggests that an emergency call gets through to or reaches the police.

Because erreichen focuses on the idea of reaching someone or getting through to them.

Compare:

• die Polizei anrufen = to call the police
• die Polizei erreichen = to reach the police / get through to the police

So erreicht can suggest that the emergency call successfully gets to the police, not just that someone attempted the call.

That nuance is often useful in situations where making contact is important.

Yes. German is flexible with adverbial phrases like während des Einbruchs.

You could also say:

• Während des Einbruchs erreicht der Notruf die Polizei.

That is still correct. The verb stays in the second position in a main clause, so if you move Während des Einbruchs to the front, the subject comes after the verb:

• Während des Einbruchs
  • erreicht
    • der Notruf
      • die Polizei

This is a very common German word-order pattern.

In German, all nouns are capitalized.

So in this sentence:

• Notruf is a noun
• Polizei is a noun
• Einbruch is a noun

That is why they begin with capital letters.

This is one of the most noticeable spelling differences between English and German.

Yes, noun gender is something you usually have to learn together with the noun.

Here they are:

• der Notruf = masculine
• die Polizei = feminine
• der Einbruch = masculine

It is best to memorize nouns with their article:

• der Notruf
• die Polizei
• der Einbruch

That makes it much easier to build correct case forms later, such as:

• des Einbruchs
• die Polizei
• der Notruf

Grammatically, it attaches to the whole clause and most naturally tells you when the event of the sentence happens.

So the basic idea is:

• the emergency call reaches the police during the burglary

In practice, that usually means the reaching/contact happens during that time. Context could make the exact interpretation more specific, but the phrase is functioning as a time expression for the sentence as a whole.

It can mean both, depending on context.

Common meanings of Notruf include:

• an emergency call
• the emergency number/service

In this sentence, because Notruf is the thing that reaches the police, it is understood as the emergency call, not the emergency number itself.

Context decides which meaning is intended.