Jeg vil betale lånet af, før renten stiger.

Because vil is a modal verb, and modal verbs are followed by the infinitive form of the next verb. So Danish says vil betale, not vil betaler.

You see the same pattern with other modals too:

• Jeg kan betale
• Jeg skal betale
• Jeg må betale

Not exactly. Vil can express several related ideas, such as:

• intention
• willingness
• desire
• future meaning

In this sentence, it most naturally sounds like a plan or intention. Danish often uses the present tense for future meaning, so using vil adds a sense of decision or intention rather than being just a neutral future marker.

Because betale ... af is a particle-verb expression. The af belongs with betale, but it is often separated and placed after the object.

So:

• betale lånet af
• betale det af

This is similar to English phrasal verbs such as pay off.

Yes, af matters.

• betale lånet af means to pay off / repay the loan
• betale lånet is less specific and can sound more like paying the loan payment or paying toward the loan

So af makes the idea of reducing or clearing the debt much clearer.

Because Danish usually puts the definite article at the end of the noun.

So:

• et lån = a loan
• lånet = the loan

and:

• en rente = an interest rate / interest
• renten = the interest rate / the interest

The endings also show gender:

• lån is a neuter noun, so it takes -et
• rente is a common-gender noun, so it takes -en

Because the sentence is talking about a specific interest rate, not just the general concept of interest. In context, it means the interest rate on the loan or the relevant interest rate being discussed.

So Danish uses the definite form renten.

In a financial sentence like this, renten usually means the interest rate. In everyday Danish, people often say renten stiger or renten falder when talking about rates going up or down.

So even if English sometimes distinguishes interest from interest rate, Danish rente often covers that whole idea.

Danish normally uses the present tense after time words like før, når, and efter, even when the meaning is future.

So før renten stiger is normal Danish. English does something very similar:

• before the interest rate rises not
• before the interest rate will rise

Før means before, and here it introduces a subordinate clause: før renten stiger.

Inside that subordinate clause, the word order is the normal subject + verb order:

• renten stiger

So the sentence is made of:

• main clause: Jeg vil betale lånet af
• subordinate clause: før renten stiger

Because før renten stiger is a subordinate clause, and many Danish writers place a comma before subordinate clauses.

You may also see the sentence written without that comma:

• Jeg vil betale lånet af før renten stiger.

Both styles occur, depending on the comma system being used. So the comma in your sentence is normal, but you may also encounter sentences without it.

Yes, absolutely. That version is also correct.

When the subordinate clause comes first, the main clause follows normal Danish verb-second word order:

• Før renten stiger, vil jeg betale lånet af

That is why it becomes vil jeg, not jeg vil.

Yes, you could, and it is closely related.

A useful rough distinction is:

• afbetale lånet = repay the loan, often with focus on the repayment process or installments
• betale lånet af = pay off the loan, often sounding a bit more like clearing the debt

In real life, the two can overlap, but learners will often hear both.