Hvis vejledningen ikke er nøjagtig nok, laver folk jo let fejl.

Because this part is a subordinate clause introduced by hvis (if).

In Danish, sentence adverbs like ikke usually come before the finite verb in subordinate clauses:

• Hvis vejledningen ikke er nøjagtig nok ...

But in a main clause, the finite verb usually comes before ikke:

• Vejledningen er ikke nøjagtig nok.

So this is a very common Danish word-order pattern:

• main clause: verb + ikke
• subordinate clause: ikke
  • verb

Because Danish follows the V2 rule in main clauses: the finite verb must be in second position.

Here, the sentence begins with the subordinate clause:

• Hvis vejledningen ikke er nøjagtig nok, ...

That whole clause takes the first position. So in the main clause, the finite verb must come next:

• laver

and then the subject:

• folk

So:

• Hvis ..., laver folk jo let fejl.

Compare:

• Folk laver jo let fejl.
• Hvis vejledningen ikke er nøjagtig nok, laver folk jo let fejl.

This inversion is normal after an initial clause or other fronted element.

Jo is a very common Danish modal particle. It often does not have one perfect English translation.

In this sentence, jo adds the sense of:

• after all
• of course
• as you know
• naturally

So it suggests that this is something obvious or unsurprising:

• Hvis vejledningen ikke er nøjagtig nok, laver folk jo let fejl.
• If the instructions aren’t accurate enough, people will naturally/obviously easily make mistakes.

Very often, jo is better understood by its effect on tone than by a single English word.

No. Here nok means enough / sufficiently, not probably.

In Danish, nok can mean different things depending on context:

1. enough / sufficiently

   • nøjagtig nok = accurate enough

2. probably / I suppose

   • Det er nok rigtigt. = That is probably true.

In your sentence, because nok follows an adjective (nøjagtig), it clearly means enough:

• ikke nøjagtig nok = not accurate enough

Vejledningen is the definite form of vejledning.

• en vejledning = an instruction guide / a set of instructions / guidance
• vejledningen = the instructions / the guidance / the manual

Danish often adds the definite article as an ending:

• -en for many common nouns

So:

• vejledning = indefinite
• vejledningen = definite

The sentence is talking about a specific set of instructions or guidance, so the definite form is used.

Vejledning can mean several related things, depending on context:

• guidance
• instructions
• directions
• manual / guidance document

In this sentence, it most naturally means something like:

• the instructions
• the guidance

because it is something that can be not accurate enough, causing people to make mistakes.

So the word is a bit broader than just one fixed English translation.

Yes, lave often means make or do, and in Danish lave fejl is a normal expression meaning:

• make mistakes

So:

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

This is just the natural collocation in Danish. English learners often want to translate word by word, but it is best to learn lave fejl as a chunk.

Folk here means people in a general sense.

• folk = people, people in general
• mennesker = human beings, people as persons

In everyday Danish, folk is very common when talking generally about what people do:

• Folk laver fejl. = People make mistakes.

Using mennesker here would sound more formal, more philosophical, or less natural in ordinary speech.

Because let is an adverb modifying the verbal idea laver fejl.

• let = easily

So the structure is:

• laver = make
• folk = people
• jo = after all / naturally
• let = easily
• fejl = mistakes

In Danish main clauses, adverbs like jo and let often appear after the subject and before the object:

• Folk laver jo let fejl.

So let is in a normal adverb position here.

Because fejl here means mistakes in a general, indefinite sense.

Danish often uses a bare noun when speaking generally:

• lave fejl = make mistakes

Compare:

• De lavede en fejl. = They made a mistake.
• De laver ofte fejl. = They often make mistakes.

So fejl here is not the mistakes or a mistake, but just mistakes in general.

Yes:

• Hvis vejledningen ikke er nøjagtig nok, laver folk let fejl.

That is grammatically fine.

Adding jo changes the tone, not the basic meaning. With jo, the speaker sounds as if the point is obvious, shared, or unsurprising:

• ... laver folk jo let fejl. = ... people will naturally make mistakes.

Without jo, the statement sounds more neutral and matter-of-fact.

Because the sentence begins with a subordinate clause:

• Hvis vejledningen ikke er nøjagtig nok, ...

The comma marks the boundary before the main clause:

• ..., laver folk jo let fejl.

This is standard Danish punctuation with an introductory subordinate clause. It also helps make the structure easier to see:

1. Hvis vejledningen ikke er nøjagtig nok = subordinate clause
2. laver folk jo let fejl = main clause

Sometimes yes, but not always with exactly the same nuance.

• nøjagtig = accurate, exact
• præcis = precise, exact

In this sentence, nøjagtig nok fits well if the idea is that the instructions are not accurate or exact enough. Præcis nok could also work in some contexts, but nøjagtig is very natural here.

So the original sentence sounds normal and idiomatic.