Jeg arbejder ikke om fredagen.

Arbejder is the present tense of at arbejde = to work.

So Jeg arbejder means I work or I am working, depending on context. Danish does not usually make the same present simple / present continuous distinction that English does.

In this sentence:

• Jeg arbejder ikke = I do not work / I am not working

Because the sentence is about a usual time pattern, the natural English meaning is I don’t work on Fridays.

In a normal main clause, Danish usually places ikke after the finite verb.

So:

• Jeg arbejder ikke ...
• literally: I work not ...

That is standard Danish word order.

A simple pattern is:

• subject + verb + ikke + other information

Examples:

• Jeg spiser ikke kød. = I do not eat meat.
• Hun kommer ikke i morgen. = She is not coming tomorrow.

This is different from English, which usually needs do not:

• I do not work rather than I work not.

Here om means something like on or during, in the sense of a repeated time.

So om fredagen means on Fridays / on Friday(s) as a habit.

This use of om is common with recurring times:

• om morgenen = in the morning
• om aftenen = in the evening
• om sommeren = in the summer
• om fredagen = on Fridays

So in this sentence, om is not about physical direction or movement. It is a time expression.

Fredagen is the definite singular form of fredag:

• fredag = Friday
• fredagen = the Friday

But in expressions like om fredagen, Danish often uses the definite form to express a general repeated time.

So:

• om fredagen = on Fridays / on Friday, as a usual thing

This may feel strange to an English speaker, because English would normally use the plural:

• on Fridays

Danish uses a different structure here.

In this sentence, om fredagen normally means every Friday / on Fridays in general.

So:

• Jeg arbejder ikke om fredagen.
• = I don’t work on Fridays.

If you want to talk about one specific upcoming Friday, Danish would usually say something else, for example:

• på fredag = this coming Friday

So:

• Jeg arbejder ikke på fredag. = I’m not working this Friday.
• Jeg arbejder ikke om fredagen. = I don’t work on Fridays.

That difference is very important.

Yes, but it means something different.

Compare:

• Jeg arbejder ikke om fredagen.
  = I do not work on Fridays.
  habit / regular schedule

• Jeg arbejder ikke på fredag.
  = I am not working this Friday.
  one specific Friday

So both are correct, but they are used in different situations.

Because Danish forms negation differently from English.

English often needs do-support:

• I do not work

Danish does not use an extra verb like do in this kind of sentence. It simply uses the main verb plus ikke:

• Jeg arbejder ikke

This is one of the big structural differences between English and Danish.

A helpful breakdown is:

• Jeg = I
• arbejder = work / am working
• ikke = not
• om = on / during
• fredagen = Friday in the definite form, used here in a recurring-time expression

So the sentence is literally close to:

• I work not on the Friday

But the natural English translation is:

• I don’t work on Fridays

You can move time expressions around, but the word order rules of Danish still apply.

The neutral version is:

• Jeg arbejder ikke om fredagen.

You could also put the time expression first:

• Om fredagen arbejder jeg ikke.

That gives a bit more focus to on Fridays.

Notice what happens then:

• the time expression comes first
• the verb still stays in the second position
• so arbejder comes before jeg

This is a very important Danish rule, often called V2 word order.

Yes, arbejder can be tricky for learners.

A rough guide is that it sounds approximately like:

• AR-bye-der
  or more smoothly
• AR-bai-er / AR-bye-er

The exact pronunciation depends on accent and speaking speed, and the middle of the word often becomes less clear in natural speech.

A few useful points:

• j in Danish often sounds like English y
• the ending -er is often pronounced quite lightly
• spoken Danish tends to reduce syllables, so the word may sound shorter than its spelling suggests

It is best to listen to native audio for this one, because the spelling is not very transparent for English speakers.

Usually, no, not in standard neutral Danish for this meaning.

If you want to say I don’t work on Fridays, the natural expression is:

• Jeg arbejder ikke om fredagen.

If you mean this Friday, say:

• Jeg arbejder ikke på fredag.

A bare fredag without om or på would normally sound incomplete or unnatural to many learners in this context.

So for practical purposes, it is best to learn:

• om fredagen = on Fridays
• på fredag = this Friday

Not by itself. Om fredagen only tells you the day/time frame, not a smaller part of the day.

So:

• Jeg arbejder ikke om fredagen.
• normally means I don’t work on Fridays

If you want to be more specific, you add more detail:

• Jeg arbejder ikke om fredagen om eftermiddagen.
  = I don’t work on Friday afternoons.

But without extra words, the sentence refers to Fridays generally, not specifically the afternoon, evening, or morning.