Die Nachbarin bringt ihre Bohrmaschine mit, weil unsere alte Bohrmaschine nicht mehr funktioniert.

Nachbarin means female neighbor. The ending -in is a very common way to form a feminine noun from a masculine one:

• der Nachbar = male neighbor
• die Nachbarin = female neighbor

So die is used because Nachbarin is feminine.

Because the verb is mitbringen, which is a separable verb.

In a main clause, the prefix separates:

• Sie bringt ihre Bohrmaschine mit.

The basic verb bringt goes in the usual verb position, and the prefix mit moves to the end.

If the verb is not separated, it stays together:

• infinitive: mitbringen
• subordinate clause: ..., weil sie ihre Bohrmaschine mitbringt.

Mitbringen means to bring along or to bring with you.

So bringen is just to bring, while mitbringen adds the idea of bringing something along to a place or situation.

Here, the idea is that the neighbor is not just bringing a drill in general; she is bringing her drill along.

In this sentence, ihre means her, referring to die Nachbarin.

German ihr-/ihre- forms can sometimes mean different things depending on context, including her or their, but here the meaning is clear from the singular subject die Nachbarin.

Also, note this important detail:

• ihre with a lowercase i = her/their
• Ihre with a capital I = formal your

So here it is definitely not formal your.

It is accusative, because it is the direct object of bringt.

Ask yourself: what is the neighbor bringing?

Answer: ihre Bohrmaschine

That makes it the direct object.

Because with feminine singular, the forms often look the same in nominative and accusative.

Compare:

• nominative: ihre Bohrmaschine
• accusative: ihre Bohrmaschine

So the case is different, but the form happens to stay the same.

This is very common in German. You often have to identify the case from the sentence function, not just from the visible ending.

Because weil introduces a subordinate clause, and in German subordinate clauses, the conjugated verb usually goes to the end.

Main clause:

• Die Nachbarin bringt ihre Bohrmaschine mit.

Subordinate clause with weil:

• ..., weil unsere alte Bohrmaschine nicht mehr funktioniert.

That final verb position is one of the most important word-order patterns in German.

Nicht mehr means no longer or not anymore.

So:

• funktioniert nicht mehr = no longer works

This is a very common expression in German:

• Ich wohne nicht mehr in Berlin. = I no longer live in Berlin.
• Er arbeitet nicht mehr hier. = He doesn’t work here anymore.

This phrase means our old drill.

Here:

• unsere = our
• alte = old
• Bohrmaschine = drill

The full phrase is the subject of the weil clause, so it is in the nominative.

The adjective ending in alte is there because German adjectives change depending on what comes before them and what case/gender/number the noun has. Here the noun is feminine singular, and after a possessive like unsere, the adjective takes -e in this form:

• unsere alte Bohrmaschine

Because Bohrmaschine is a compound noun, and in German the last part of a compound determines the gender.

• bohren = to drill
• die Maschine = machine

So:

• die Bohrmaschine = drill

Since Maschine is feminine, the whole compound Bohrmaschine is feminine too.

Yes, the meaning would be very similar, but the grammar changes.

With weil, the verb goes to the end:

• Die Nachbarin bringt ihre Bohrmaschine mit, weil unsere alte Bohrmaschine nicht mehr funktioniert.

With denn, the clause keeps normal main-clause word order:

• Die Nachbarin bringt ihre Bohrmaschine mit, denn unsere alte Bohrmaschine funktioniert nicht mehr.

So both can mean because, but weil and denn do not behave the same way grammatically.

Because in German, a subordinate clause is normally separated from the main clause with a comma.

Since weil unsere alte Bohrmaschine nicht mehr funktioniert is a subordinate clause, the comma is required.

This is stricter in German than in English, so learners often need to pay special attention to it.