Hun bliver altid i tvivl, når navigationen siger venstre, men skiltet ved rundkørslen viser en anden afkørsel.

Because bliver means becomes / gets, while er means is.

So Hun bliver altid i tvivl means She always becomes uncertain / gets confused. It describes a change of state: she starts out fine, then becomes unsure.

If you said Hun er altid i tvivl, that would mean She is always uncertain, which sounds more like a general permanent state.

I tvivl is a fixed expression meaning in doubt, uncertain, or not sure.

So:

• at være i tvivl = to be in doubt / to be unsure
• at blive i tvivl = to become unsure

It is very common in Danish, and you should learn it as a chunk rather than translating each word separately every time.

In Danish main clauses, the finite verb usually comes in second position. This is the V2 rule.

Here the structure is:

• Hun = subject
• bliver = finite verb
• altid = adverb
• i tvivl = complement

So the normal order is:

Hun bliver altid i tvivl

Not:

Hun altid bliver i tvivl

The adverb altid usually comes after the finite verb in a main clause.

Here når means when in the sense of whenever or when that situation happens.

So:

når navigationen siger venstre
= when / whenever the navigation says left

This fits because it describes a repeated situation.

By contrast, da is usually used for a specific event in the past:

• Da navigationen sagde venstre, blev hun i tvivl
  = When the navigation said left, she became unsure

So:

• når = repeated/general/future situations
• da = one specific past situation

Navigationen is the definite form, meaning the navigation / the GPS.

In Danish, definiteness is often added to the end of the noun:

• en navigation = a navigation device / a GPS
• navigationen = the navigation / the GPS

In this sentence, it refers to a specific navigation system, so the definite form is natural.

Yes. In Danish, this is a very natural shortened way of speaking.

Literally, siger venstre means says left, but the fuller idea is something like:

• siger, at man skal til venstre
• siger, at hun skal dreje til venstre

In everyday language, especially with GPS directions, Danish often leaves out words that are understood from context.

So navigationen siger venstre is idiomatic and natural.

Men means but. It connects two contrasting ideas:

• the GPS says one thing
• the sign shows something else

So the contrast is:

navigationen siger venstre, men skiltet ... viser en anden afkørsel

This is exactly like English but.

These are the definite forms of the nouns.

• et skilt = a sign

• skiltet = the sign

• en rundkørsel = a roundabout
• rundkørslen = the roundabout

Danish nouns have common gender and neuter gender:

• en words usually take -en in the definite singular
• et words usually take -et in the definite singular

So:

• skiltet because skilt is an et noun
• rundkørslen because rundkørsel is an en noun

Ved often means by, at, or near, depending on context.

So skiltet ved rundkørslen means:

• the sign by the roundabout
• the sign at the roundabout
• the sign near the roundabout

All of those are good English translations. The exact choice depends on how natural you want the English to sound.

Afkørsel means exit, turn-off, or off-ramp, depending on context.

In a roundabout, it usually means exit:

• første afkørsel = first exit
• anden afkørsel = second exit

So viser en anden afkørsel means shows a different exit.

Here it most naturally means a different exit.

En anden can mean:

• another
• a different

In this sentence, the important idea is contrast: the sign indicates a different choice from the GPS.

So a different exit is the best explanation here.

Because with navigation language, Danish often uses short instruction-style expressions.

So:

• siger venstre = literally says left
• fuller form: siger til venstre or siger, at man skal til venstre

The shorter form sounds natural in the context of GPS instructions. It is similar to how a device in English might simply say Left or Turn left.

Yes. After når, Danish uses subordinate clause word order.

In this clause:

når navigationen siger venstre

the subject navigationen comes before the verb siger, which is normal.

If you add an adverb like ikke, you can see the subordinate structure more clearly:

• når navigationen ikke siger venstre

In subordinate clauses, sentence adverbs like ikke usually come before the main verb.

That is different from many main clauses.

Yes. If a subordinate clause comes first, the main clause still follows the Danish V2 pattern, so the finite verb comes before the subject in the main clause.

Original:

Hun bliver altid i tvivl, når navigationen siger venstre ...

Reordered:

Når navigationen siger venstre, bliver hun altid i tvivl ...

Notice the change:

• Hun bliver ...
• Når ..., bliver hun ...

That inversion is very important in Danish main clauses.

Yes. Hun means she and is the subject form.

Compare:

• hun = she
• hende = her

So here it must be hun, because she is doing the action of becoming unsure:

Hun bliver altid i tvivl

Not:

Hende bliver altid i tvivl

It has three main parts:

1. Hun bliver altid i tvivl
   = main clause

2. når navigationen siger venstre
   = subordinate clause introduced by når

3. men skiltet ved rundkørslen viser en anden afkørsel
   = second main clause introduced by men

So the sentence is basically:

She gets confused when X, but Y says something different.

That makes it a good example of how Danish combines:

• a main clause,
• a når clause,
• and a contrasting clause with men.