Han fleiper om feilen.

Fleiper is the present tense of the verb å fleipe.

So:

• å fleipe = to joke, to kid around
• fleiper = joke / is joking

In this sentence, Han fleiper om feilen, it means that he is joking about the mistake/error.

This verb is a bit informal and conversational.

In Bokmål, many verbs in the present tense end in -er.

So:

• å fleipe
• han fleiper

This is the normal present-tense pattern for this verb.

A few examples with the same kind of pattern:

• å snakke → snakker
• å spise → spiser
• å fleipe → fleiper

Om often means about.

So in this sentence:

• fleiper om = jokes about

That is why Han fleiper om feilen literally matches He jokes about the mistake.

This is a very common use of om:

• snakke om noe = talk about something
• tenke på noe = think about something
• fleipe om noe = joke about something

So this is not random; it is the preposition that goes naturally with the idea here.

Feilen is the definite form of feil.

• en feil = a mistake / an error
• feilen = the mistake / the error

Norwegian usually adds the definite article to the end of the noun instead of putting a separate word in front.

So:

• en bil = a car
• bilen = the car

and:

• en feil = a mistake
• feilen = the mistake

So om feilen means about the mistake, not just about a mistake.

Yes, feil can be both a noun and an adjective/adverb-like word, depending on the sentence.

Here it is a noun:

• en feil = a mistake, an error

But in other sentences it can mean wrong:

• Det er feil. = That is wrong.
• Jeg tok feil. = I was mistaken.

In Han fleiper om feilen, the ending -en clearly shows that it is a noun in the definite form.

It is in the present tense.

• Han = he
• fleiper = jokes / is joking
• om feilen = about the mistake

So depending on context, English might translate it as:

• He jokes about the mistake.
• He is joking about the mistake.

Norwegian present tense often covers both the simple present and the present continuous that English separates.

This is the normal word order for a simple main clause in Norwegian:

subject + verb + rest

So:

• Han = subject
• fleiper = verb
• om feilen = prepositional phrase

Very straightforward.

If you move something else to the front, Norwegian usually keeps the verb in second position:

• Om feilen fleiper han.

That is grammatical, but much less natural in everyday speech unless you are emphasizing about the mistake.

So the original sentence is the most neutral and natural order.

Yes, often you could.

• å spøke = to joke
• å fleipe = to joke, kid around

Both can work, but fleipe often sounds a bit more casual or colloquial.

So:

• Han spøker om feilen = He jokes about the mistake
• Han fleiper om feilen = He jokes about the mistake

The difference is mostly one of tone and style, not basic meaning.

A helpful rough guide is:

• feil sounds a bit like English file, but not exactly
• feilen is roughly FAY-len

The ei in Norwegian often sounds like the vowel in English say followed by a light glide, though exact pronunciation varies a bit by accent.

The ending -en is the definite ending, and it is usually pronounced lightly.

Usually han means he, so it normally refers to a male person.

However, Norwegian can also use han for some masculine nouns when they are personified, but in a simple learner sentence like this, you should understand han as he.

So the sentence most naturally means:

• He jokes about the mistake.

It is Bokmål.

Clues include:

• han for he
• fleiper as a Bokmål present form
• feilen as the definite form

A Nynorsk version might look different depending on word choice.

So if you are learning standard written Norwegian, this sentence is a normal Bokmål sentence.