Det var ikke før opplæringen begynte at hun forsto hvordan turnusen fungerer.

This is a very common Norwegian pattern meaning something like:

• It wasn’t until ... that ...
• Not before ... did ...

So in this sentence:

• Det var ikke før opplæringen begynte at hun forsto ...

the structure is:

• Det var ikke før X at Y
• It wasn’t until X that Y

Here:

• X = opplæringen begynte
• Y = hun forsto hvordan turnusen fungerer

A more literal breakdown is:

• Det var = it was
• ikke før = not before / not until
• at = that

This is a fixed and very natural way to emphasize that something happened only after a certain point.

Here, det is mainly a formal or introductory subject. It does not refer to a concrete thing.

In English, we do something similar in sentences like:

• It was not until...
• It is important that...

The it there does not point to a real object; it is just part of the sentence structure. Norwegian det often works the same way.

So in Det var ikke før ... at ..., the det is required by the construction rather than carrying a separate meaning.

In this sentence, at introduces the main result part of the construction:

• Det var ikke før X at Y
• It wasn’t until X that Y

So at hun forsto ... means that she understood ...

This at is a normal part of the pattern. Without it, the sentence would sound incomplete or wrong in standard Norwegian.

So think of the sentence as two linked parts:

• Det var ikke før opplæringen begynte
• at hun forsto hvordan turnusen fungerer

Opplæringen is the definite form of opplæring.

• opplæring = training
• opplæringen = the training

In Norwegian, nouns often take a suffix to show definiteness:

• en bil = a car
• bilen = the car

Likewise:

• en turnus = a shift schedule / rota / rotation
• turnusen = the shift schedule / the rota

Here, opplæringen is definite because the sentence is referring to a specific training period, not training in general.

Begynne can be used in different ways.

1. Begynne on its own:

   • Opplæringen begynte.
   • The training started.

2. Begynne å + infinitive:

   • Hun begynte å jobbe.
   • She started to work.

In your sentence, opplæringen is the thing that started, so begynte is complete by itself.

• opplæringen begynte = the training began

There is no need for å because no second verb follows.

Because the sentence describes a past moment of realization.

• forstår = understands
• forsto = understood

So:

• hun forsto = she understood

The whole sentence talks about when that understanding finally happened. It says she did not understand it before the training began, and then at that point she did.

This is a very common thing in both Norwegian and English.

Even though the main event is in the past (hun forsto), the embedded clause can be in the present if it refers to something still generally true or still valid:

• hun forsto hvordan turnusen fungerer
• she understood how the shift system works

This suggests that the way the rota/system works is a general fact, not just something true in the past.

Compare:

• Hun forsto hvordan turnusen fungerte. = She understood how the rota worked.
  This focuses more on how it worked at that past time.

• Hun forsto hvordan turnusen fungerer. = She understood how the rota works.
  This sounds like she came to understand the system in general, possibly still true now.

So the present tense here is not strange; it is often the most natural choice.

Turnus can mean different but related things depending on context. Common meanings include:

• a work rota
• a shift schedule
• a rotation system
• a duty roster

In healthcare and some other fields, turnus often refers to the pattern of shifts or scheduled rotations.

So hvordan turnusen fungerer means something like:

• how the shift system works
• how the rota works
• how the schedule rotation works

The exact English translation depends on context.

Because hvordan turnusen fungerer is an embedded question, not a direct question.

In Norwegian:

1. Direct question:

   • Hvordan fungerer turnusen?
   • How does the rota work?

2. Embedded question:

   • Hun forsto hvordan turnusen fungerer.
   • She understood how the rota works.

In embedded questions, Norwegian usually keeps statement word order:

• question word + subject + verb

So:

• hvordan turnusen fungerer not
• hvordan fungerer turnusen

This is similar to English:

• Direct: How does the rota work?
• Embedded: She understood how the rota works.

Yes, but the emphasis would change.

For example:

• Da opplæringen begynte, forsto hun hvordan turnusen fungerer. = When the training began, she understood how the rota works.

This is grammatically fine, but it does not emphasize the delay as strongly.

The original:

• Det var ikke før opplæringen begynte at hun forsto ...

strongly highlights that she did not understand it earlier. It focuses on the turning point.

So the original sentence is more emphatic and more precise if you want to stress only then / not until then.

Because after at, Norwegian uses normal subordinate clause word order.

Compare:

• Main clause: Hun forsto
• Subordinate clause after at: at hun forsto

In subordinate clauses, the subject normally comes before the finite verb.

So:

• at hun forsto = correct
• at forsto hun = incorrect

This is an important difference from main clauses in Norwegian, where the verb often comes in second position.

Very often, yes, especially in this kind of sentence.

• ikke før literally means not before
• but in natural English, not until is usually the best translation

Examples:

• Ikke før mandag = not until Monday
• Det var ikke før da at ... = It wasn’t until then that ...

So while not before is closer word-for-word, not until is usually the most natural meaning.

No, that would not be correct.

The normal pattern is:

• Det var ikke før X at Y

So:

• Det var ikke før opplæringen begynte at hun forsto ...

The før is followed directly by the time/event clause:

• før opplæringen begynte

Then at introduces the result clause:

• at hun forsto ...

So the sentence is divided like this:

• ikke før + event
• at + result

not:

• ikke før at + event

The main verb forms are:

• var = past tense of å være = was
• begynte = past tense of å begynne = began
• forsto = past tense of å forstå = understood
• fungerer = present tense of å fungere = works / functions

So the sentence mixes past and present in a natural way:

• past for the moment of realization
• present for how the system works in general

That combination is very common and worth getting used to.