Vores nye kollega har det med at være både grundig og nøjagtig, og derfor stoler chefen på hende.

It is a common idiomatic expression meaning to tend to, to be inclined to, or to have a habit of doing something.

So har det med at være både grundig og nøjagtig means that this is a typical trait or pattern of behavior, not just a one-time situation.

Here, det is part of a fixed expression. It does not point to a specific thing.

A good way to learn this is as one whole chunk:

have det med at + infinitive

Danish has several expressions like this where a small word is required even though English would not use one.

After har det med at, Danish uses the infinitive form of the verb:

have det med at + verb

So:

• har det med at være = tends to be
• har det med at glemme = tends to forget
• har det med at komme for sent = tends to arrive late

Here være is used because the sentence describes a quality or state.

They are similar, but not identical:

• grundig = thorough
• nøjagtig = accurate / precise / exact

So someone who is grundig works carefully and completely, while someone who is nøjagtig gets details correct and is precise. Using both together gives a stronger description.

It means both ... and ....

It connects two things of the same type. In this sentence, it connects two adjectives:

• både grundig og nøjagtig = both thorough and accurate

You can also use it with nouns, verbs, and longer phrases.

They are predicate adjectives after være, describing kollega.

Because kollega is singular and common gender, the base form is used:

• grundig
• nøjagtig

Very roughly:

• common gender singular: basic form
• neuter singular: often -t
• plural/definite contexts: often -e

So the form matches kollega.

Because vores already acts like a determiner. In Danish, you normally do not use en/et together with a possessive.

Compare:

• en ny kollega = a new colleague
• vores nye kollega = our new colleague

Also notice that the adjective becomes nye after the possessive.

After possessives like min, din, vores, deres, adjectives usually take the -e form.

So:

• en ny kollega
• vores nye kollega

This is one of the common places where Danish uses the -e adjective ending.

No. Kollega is not specifically male or female.

The word itself just means colleague. You only learn that this colleague is female from the pronoun hende later in the sentence.

Because Danish main clauses follow the V2 rule: the finite verb usually comes in the second position.

When derfor is placed first, the verb must come next:

• Derfor stoler chefen på hende

So the subject chefen comes after the verb. This word order is very common in Danish.

Because the normal expression is:

at stole på nogen = to trust someone / rely on someone

This is a verb + preposition combination that has to be learned together. Danish often works this way, just like English has combinations such as listen to, depend on, or believe in.

Because after a preposition, Danish uses the object form of the pronoun.

• hun = subject form
• hende = object form

Since the pronoun comes after på, you need hende:

• på hende = on her / her

Chefen is the definite form, meaning the boss.

In Danish, definiteness is often shown by adding an ending to the noun:

• en chef = a boss
• chefen = the boss

So here it refers to a specific boss, presumably the one relevant in the situation.