Hon skär paprika på skärbrädan medan jag värmer soppan.

These are the Swedish subject pronouns:

• hon = she
• jag = I

They are used just like English subject pronouns because they are doing the actions in the sentence:

• Hon skär ... = She cuts/is cutting ...
• ... medan jag värmer ... = ... while I heat/am heating ...

Both are in the present tense.

• skär = cuts / is cutting
• värmer = heats / is heating

In Swedish, the present tense often covers both the simple present and the present progressive in English. So:

• Hon skär paprika can mean She cuts pepper or, more naturally here, She is cutting pepper
• jag värmer soppan can mean I heat the soup or I am heating the soup

The exact English translation depends on context.

Swedish usually does not need a separate verb like English is to show an action in progress.

English:

• She is cutting
• I am heating

Swedish:

• Hon skär
• Jag värmer

So Swedish often uses the plain present tense where English prefers the be + -ing form.

Here, paprika is being used as an indefinite substance/object noun, roughly like pepper or bell pepper in a general sense.

So Hon skär paprika means:

• She is cutting pepper / bell pepper
• more naturally: She is cutting up a bell pepper / some pepper

Swedish often leaves out the article when talking about food or material in a general or non-counted way.

Compare:

• Hon skär paprika = She is cutting pepper / a bell pepper / some pepper
• Hon skär en paprika = She is cutting a bell pepper
  This is more specific if you want to emphasize one pepper

It can mean either, depending on context.

• paprika = bell pepper / sweet pepper
• paprika can also mean paprika powder

In this sentence, because of skär (cuts) and på skärbrädan (on the cutting board), it clearly means the vegetable, not the spice.

skärbrädan is the definite form of skärbräda.

• en skärbräda = a cutting board
• skärbrädan = the cutting board

Swedish usually adds the definite article as a suffix at the end of the noun:

• en bok → boken
• en stol → stolen
• en skärbräda → skärbrädan

So på skärbrädan means on the cutting board.

It is a compound noun:

• skär = related to cut
• bräda = board / plank

So skärbräda literally means something like cut-board, i.e. cutting board.

Swedish uses compounds very freely, much more than English in some cases.

Also notice that skär appears both in:

• Hon skär = She cuts
• skärbräda = cutting board

They are related in meaning.

på usually means on.

So:

• på skärbrädan = on the cutting board

This matches English pretty closely. The action happens on the surface of the board, so på is the natural choice.

medan means while.

It connects two actions happening at the same time:

• Hon skär paprika = She is cutting pepper
• medan jag värmer soppan = while I am heating the soup

So the whole sentence shows two simultaneous actions.

Because medan introduces a subordinate clause, and Swedish word order changes in subordinate clauses.

In a normal main clause, Swedish often has the verb in second position:

• Jag värmer soppan = I am heating the soup

But after a subordinating word like medan, the subject usually comes before the verb:

• medan jag värmer soppan

So this is the normal pattern:

• medan + subject + verb

Other common subordinating words that work similarly are:

• att = that
• när = when
• eftersom = because

soppan is the definite form of soppa.

• soppa = soup
• soppan = the soup

So:

• jag värmer soppa = I am heating soup (general, less specific)
• jag värmer soppan = I am heating the soup (a specific soup we already know about)

The -n ending marks definiteness because soppa is an en-word.

Because Swedish usually puts the definite article at the end of the noun instead of using a separate word like English the.

Examples:

• bok = book

• boken = the book

• soppa = soup

• soppan = the soup

• skärbräda = cutting board
• skärbrädan = the cutting board

So in this sentence:

• skärbrädan = the cutting board
• soppan = the soup

Grammatically, yes:

• She cuts pepper on the cutting board while I heat the soup

But in natural English, this sounds less likely for a scene happening right now. Because the sentence describes ongoing actions, English usually prefers:

• She is cutting pepper on the cutting board while I am heating the soup

Swedish does not make that distinction the same way, so the plain present tense is enough.

Yes, it is natural and grammatical.

It sounds like a straightforward description of two people doing things in the kitchen at the same time.

A few small variations are also possible depending on what you want to emphasize, for example:

• Medan jag värmer soppan skär hon paprika på skärbrädan. = While I am heating the soup, she is cutting pepper on the cutting board.

That version puts the while-clause first, but the meaning is basically the same.