Die Personalabteilung schreibt das Arbeitszeugnis.

These are the grammatical genders of the two nouns:

• die Personalabteilung = feminine
• das Arbeitszeugnis = neuter

In German, every noun has a grammatical gender, and the article must match it. This does not necessarily have anything to do with biological sex. You simply have to learn the noun together with its article.

A useful habit is to learn:

• die Personalabteilung
• das Arbeitszeugnis

not just Personalabteilung and Arbeitszeugnis on their own.

Yes, partly. The articles show both gender and case.

In this sentence:

• Die Personalabteilung is the subject → it is in the nominative
• das Arbeitszeugnis is the direct object → it is in the accusative

Here, the forms happen to look like this:

• feminine nominative: die
• neuter accusative: das

So the sentence structure is:

• Die Personalabteilung = the HR department
• schreibt = writes / is writing
• das Arbeitszeugnis = the job reference

Note that for neuter, nominative and accusative are both das, so you do not see a change here.

Because the subject is third person singular: die Personalabteilung = the HR department = it.

The verb schreiben is conjugated like this in the present tense:

• ich schreibe
• du schreibst
• er/sie/es schreibt
• wir schreiben
• ihr schreibt
• sie/Sie schreiben

Since die Personalabteilung is singular, German uses schreibt.

It can mean either, depending on context.

German present tense often covers both:

• writes
• is writing

So Die Personalabteilung schreibt das Arbeitszeugnis could mean:

• The HR department writes the job reference
• The HR department is writing the job reference

If German wants to make the ongoing action especially clear, it usually relies on context rather than a special tense like English is writing.

This is the normal German main clause word order:

Subject + verb + object

So:

• Die Personalabteilung = subject
• schreibt = verb
• das Arbeitszeugnis = object

German main clauses usually put the conjugated verb in second position. Here the subject comes first, so the verb comes right after it.

It is a compound noun, which is very common in German.

You can break it down into:

• Personal = personnel / staff / HR-related
• Abteilung = department

Together:

• Personalabteilung = HR department / personnel department

In German, compound nouns are usually written as one word.

The final part often determines the gender, and here the last part is Abteilung, which is feminine:

• die Abteilung
• therefore die Personalabteilung

It is also a compound noun:

• Arbeit = work
• Zeugnis = certificate / reference / report

So:

• Arbeitszeugnis = a work-related certificate/reference, usually translated as job reference or employment reference

The last part is Zeugnis, which is neuter:

• das Zeugnis
• therefore das Arbeitszeugnis

This is another useful pattern in German compounds: the last noun usually determines the gender.

Because with neuter nouns, the definite article is the same in both nominative and accusative:

• nominative neuter: das
• accusative neuter: das

So even though das Arbeitszeugnis is the object, the article stays das.

Compare that with a masculine noun, where you would see a change:

• nominative: der Mann
• accusative: den Mann

That is why some German sentences show the case more obviously than this one does.

No. If you want to say a job reference, it must be:

• ein Arbeitszeugnis

not einen Arbeitszeugnis

Why? Because Arbeitszeugnis is neuter.

For ein-words in the accusative:

• masculine: einen
• feminine: eine
• neuter: ein

So:

• Die Personalabteilung schreibt das Arbeitszeugnis. = the job reference
• Die Personalabteilung schreibt ein Arbeitszeugnis. = a job reference

In this sentence, the doer is Die Personalabteilung because it is the subject.

You can identify it by:

1. word order: it comes before the verb in this basic sentence
2. meaning: the HR department is the thing performing the action
3. verb agreement: schreibt matches a singular subject

The thing receiving the action is das Arbeitszeugnis, the direct object.

So:

• Who writes? → Die Personalabteilung
• What is being written? → das Arbeitszeugnis

Usually, yes, in modern business English.

A more literal translation is personnel department, but in many contexts HR department sounds more natural. The exact English translation depends on tone and context, but in German the word itself is perfectly normal and standard.

Here are a few helpful comparisons:

• Die Personalabteilung schreibt das Arbeitszeugnis.
  The HR department writes the job reference.

• Die Personalabteilungen schreiben die Arbeitszeugnisse.
  The HR departments write the job references.

Notice the changes:

• singular verb: schreibt
• plural verb: schreiben

And the plural nouns:

• die Personalabteilungen
• die Arbeitszeugnisse

This helps show that schreibt is singular, while schreiben is plural.