Jag har arbetat vid mitt skrivbord sedan klockan sju i morse.

In this sentence, Swedish uses the present perfect: jag har arbetat.

That is very common when talking about something that:

• started in the past, and
• is still relevant now, or is still continuing

English often prefers have been working in this situation:

• I have been working at my desk since seven this morning.

Swedish usually does not need a special continuous form like English does. So:

• Jag har arbetat ... sedan ... = I have been working ... since ...

A present tense form like jag arbetar would not sound as natural here with sedan klockan sju i morse.

Arbetat is the supine form of the verb arbeta.

In Swedish, the perfect tense is built like this:

• har
  • supine

So:

• arbeta = to work
• har arbetat = have worked / have been working

This is different from English grammar, so it helps to memorize it as a pattern:

• jag har arbetat
• du har arbetat
• han/hon har arbetat

Because skrivbord is an ett-word in Swedish:

• ett skrivbord = a desk

For ett-words, the possessive my is:

• mitt

Compare:

• en bok → min bok
• ett skrivbord → mitt skrivbord

So:

• vid mitt skrivbord = at my desk

Here, vid means at or by.

So:

• vid mitt skrivbord = at my desk

This is a natural way to say that someone is sitting or working at a desk.

Why not på?

• på mitt skrivbord usually means on top of my desk
• vid mitt skrivbord means at my desk, in the position where you sit/work

So the sentence is talking about location in relation to the desk, not being physically on the desk.

Here, sedan means since.

It introduces the starting point:

• sedan klockan sju i morse = since seven o’clock this morning

A useful idea:

• sedan + starting point in time = since
• sometimes sedan can also mean for, depending on the sentence

Examples:

• sedan i måndags = since Monday
• sedan förra året = since last year

In Swedish, when giving a specific clock time, it is very common to say klockan before the number.

So:

• klockan sju = seven o’clock

This is the normal way to express a time of day in many contexts.

Examples:

• klockan tre = three o’clock
• klockan halv åtta = half past seven
• sedan klockan sju = since seven o’clock

I morse means this morning.

It is a fixed expression:

• i morse = this morning
• i kväll = tonight / this evening
• i natt = tonight / last night, depending on context

The i is just part of the usual expression. You should learn i morse as one unit.

Note that morse by itself is not normally used the same way in standard modern Swedish. The natural phrase is:

• i morse

Swedish usually puts the time expression after the main part of the verb phrase in a sentence like this:

• Jag har arbetat vid mitt skrivbord sedan klockan sju i morse.

This order is very natural:

1. subject: Jag
2. verb: har
3. main verb form: arbetat
4. place: vid mitt skrivbord
5. time: sedan klockan sju i morse

You could move parts around for emphasis, but this basic order is standard and natural.

Yes. Jobba is a very common everyday verb meaning to work.

So you could say:

• Jag har jobbat vid mitt skrivbord sedan klockan sju i morse.

Difference in tone:

• arbeta sounds a bit more formal or neutral
• jobba sounds more everyday and conversational

Both are correct here.

Because Swedish does not build this idea the same way English does.

English often says:

• I have been working

Swedish normally just says:

• Jag har arbetat

So Swedish expresses the same idea without a separate word corresponding to been in this structure.

That is one of the important differences between English and Swedish:

• English often uses a continuous form
• Swedish usually does not

Yes, in some contexts Swedish uses sedan where English might use either since or for, depending on how the time expression is phrased.

For example:

• Jag har bott här sedan 2020. = I have lived here since 2020.
• Jag har bott här sedan länge. = I have lived here for a long time.

In your sentence, though, it clearly means since, because it is followed by a specific starting point:

• sedan klockan sju i morse

Yes, it is natural and correct.

It sounds like standard, clear Swedish. A native speaker might also choose slightly more everyday wording, for example:

• Jag har jobbat vid mitt skrivbord sedan klockan sju i morse.
• Jag har suttit vid skrivbordet och jobbat sedan sju i morse.

But your original sentence is absolutely normal and grammatical. It sounds a bit careful or neutral in style, which is often useful for learners.