Hvis jeg arbejder sjusket, laver jeg let fejl i opgaven.

Hvis means if. It introduces a condition:

Hvis jeg arbejder sjusket = If I work sloppily/carelessly

So the first part tells you the condition, and the second part tells you the result.

This is a very important Danish word-order rule.

In a Danish main clause, the finite verb usually comes in second position. When the sentence begins with a subordinate clause such as Hvis jeg arbejder sjusket, that whole clause takes the first position. Then the main verb must come next:

• Hvis jeg arbejder sjusket, laver jeg let fejl i opgaven.

So:

1. Hvis jeg arbejder sjusket = position 1
2. laver = position 2
3. jeg = subject after the verb

This is often called the V2 rule.

If you put the main clause first, then you get normal subject-verb order:

• Jeg laver let fejl i opgaven, hvis jeg arbejder sjusket.

Here sjusket functions adverbially: it describes how the person works.

• arbejder sjusket = works sloppily / works carelessly

In Danish, words that are adjectives in other contexts are often used adverbially too. Many adverbial forms look like the adjective’s -t form. Since sjusket already ends in -t, it stays the same.

Compare:

• et sjusket arbejde = sloppy work
• han arbejder sjusket = he works sloppily

So in your sentence, sjusket tells us the manner of working.

Sjusket usually means something like:

• sloppy
• careless
• untidy
• done without enough attention

It often suggests that someone is not being careful enough, especially in work, writing, school tasks, or practical activities.

So it is a bit stronger and more negative than simply saying someone is in a hurry. It suggests poor attention to detail.

Here let means easily or readily.

So:

• laver jeg let fejl = I easily make mistakes

It does not mean light here.

In this sentence, let is an adverb describing how easily the mistakes happen.

A very similar word is nemt. In many contexts, both are possible:

• Jeg laver let fejl
• Jeg laver nemt fejl

Both can mean I easily make mistakes, though let is often a little shorter and more compact in style.

Because lave fejl is the normal idiomatic expression in Danish.

• lave fejl = make mistakes
• lave en fejl = make a mistake

This is similar to English, where you say make a mistake, not do a mistake.

So even though lave often means make/do, the fixed expression here is lave fejl.

Because fejl here is plural indefinite: mistakes.

So:

• en fejl = a mistake
• fejl = mistakes

That gives:

• Jeg laver en fejl. = I make a mistake.
• Jeg laver fejl. = I make mistakes.

A useful thing to notice is that the singular and plural forms can look very similar:

• singular indefinite: en fejl
• plural indefinite: fejl

In your sentence, the bare noun fejl means mistakes in general.

Opgaven is the definite form: the assignment / the task / the exercise.

Danish usually adds the definite ending directly to the noun:

• en opgave = an assignment
• opgaven = the assignment

So the sentence refers to a specific assignment or task that is already known from the context.

I opgaven literally means in the assignment.

This is natural when the mistakes are understood as being inside the written work, exercise, or task itself.

So:

• fejl i opgaven = mistakes in the assignment/exercise

This is different from something like:

• arbejde på opgaven = work on the assignment

So på is often used for working on something, while i is used for errors or content inside it.

Because the sentence expresses a general truth or habitual pattern:

• whenever I work sloppily, I make mistakes

Danish often uses the present tense for this kind of general statement, just like English does in sentences such as:

• If I rush, I make mistakes.

So:

• arbejder = present tense of arbejde
• laver = present tense of lave

This is not necessarily about one specific future event. It describes what typically happens.

If you wanted a more hypothetical meaning, Danish could use a different structure, for example:

• Hvis jeg arbejdede sjusket, ville jeg let lave fejl i opgaven.

That means something more like If I worked sloppily, I would easily make mistakes in the assignment.