Betalingsfristen er neste fredag.

Betalingsfristen means the payment deadline.

It is a compound noun:

• betaling = payment
• frist = deadline / time limit

So:

• betalingsfrist = payment deadline
• betalingsfristen = the payment deadline

Norwegian very often makes compound nouns this way, more than English does.

The ending -en marks the noun as definite: the payment deadline.

Compare:

• en betalingsfrist = a payment deadline
• betalingsfristen = the payment deadline

This is very common in Norwegian. Instead of putting a separate word for the before the noun, Norwegian usually adds the definiteness to the end of the noun.

Frist is usually a masculine noun: en frist.

That gives you:

• en frist = a deadline
• fristen = the deadline

In the compound noun, the final part decides the gender:

• en betalingsfrist
• betalingsfristen

So yes, the gender matters because it affects the article and the definite ending.

Er is the present tense of å være = to be.

So:

• er = is / are

In this sentence, it links the subject to the time expression:

• Betalingsfristen er neste fredag = The payment deadline is next Friday

This works very much like English is.

In Norwegian, time expressions like neste fredag often do not need a preposition.

So Norwegian says:

• neste fredag = next Friday

Not:

• på neste fredag in this sentence

This is similar to English, where you also usually say next Friday, not on next Friday.

Neste fredag is the normal way to say next Friday when talking about an upcoming day on the calendar.

• fredag = Friday
• neste fredag = next Friday

Using the definite form fredagen would usually sound different and less natural here. For a simple calendar meaning, neste fredag is the standard choice.

The word order is straightforward:

• Betalingsfristen = subject
• er = verb
• neste fredag = time expression / complement

So the pattern is basically:

• Subject + verb + time expression

This is a very common main-clause word order in Norwegian.

Yes. Fristen for betaling er neste fredag is also correct and natural.

It means the same thing:

• betalingsfristen = the payment deadline
• fristen for betaling = the deadline for payment

The compound noun betalingsfristen is a bit more compact, while fristen for betaling is more unpacked and explicit.

Not always. Just like English next Friday, neste fredag can sometimes depend on context.

For example, if today is:

• Wednesday, most people will understand it as the coming Friday
• Friday, some people may mean the Friday one week later

If you need to be very clear, Norwegian speakers may use a full date instead.

You could say:

• En betalingsfrist er neste fredag.

But this is less likely in ordinary use unless you are introducing one deadline among several.

More natural examples of the indefinite form would be:

• Vi har en betalingsfrist neste fredag. = We have a payment deadline next Friday.
• Det er en betalingsfrist neste fredag. = There is a payment deadline next Friday.

So in your original sentence, the definite form makes sense because it refers to a specific known deadline.