Jeg føler mig mere selvsikker, når jeg forstår teksten bedre.

Because Danish often uses the reflexive expression at føle sig for to feel in the sense of to feel oneself / to feel a certain way.

So:

• Jeg føler mig træt = I feel tired
• Jeg føler mig mere selvsikker = I feel more confident

Here, mig is the reflexive pronoun, meaning myself.

A native English speaker may want to translate word-for-word, but in Danish this reflexive structure is very common with føle when talking about your state.

Jeg is the subject form: I.
Mig is the object form: me.

In this sentence:

• Jeg = the subject doing the feeling
• mig = the object in the reflexive expression føle sig

So:

• Jeg føler mig... = I feel...

This is similar to English using I vs me, even though English does not usually say I feel me.

Danish comparatives can be formed in two main ways:

1. With an ending, often -ere
2. With mere
   • adjective

In practice, many longer adjectives and many everyday expressions use mere.

So:

• selvsikker = confident
• mere selvsikker = more confident

Even if learners expect a single-word comparative, mere + adjective is very natural Danish.

Literally, selvsikker is made from:

• selv = self
• sikker = sure / secure

So the literal idea is something like self-sure.
In natural English, that is usually confident or self-confident.

Be careful: depending on context, selvsikker can be positive (confident) or slightly negative (overconfident / too sure of oneself), but in this sentence it sounds positive.

Because Danish normally uses a comma before a subordinate clause.

Here:

• Main clause: Jeg føler mig mere selvsikker
• Subordinate clause: når jeg forstår teksten bedre

So the comma helps mark that the second part depends on the first part.

This is more regular in Danish writing than in English, where commas before when are often omitted.

Når usually means when in the sense of:

• when / whenever
• something expected
• something habitual or repeated

Hvis means if and is more conditional.

So:

• Når jeg forstår teksten bedre = When/Whenever I understand the text better
• Hvis jeg forstår teksten bedre = If I understand the text better

In your sentence, når suggests a natural connection: as understanding improves, confidence improves.

Because after a subordinating conjunction like når, Danish uses subordinate clause word order.

That means the subject usually comes before the verb:

• når jeg forstår teksten bedre

Not:

• når forstår jeg teksten bedre

A very useful rule is:

• In a main clause, Danish often has verb in second position
• In a subordinate clause, that V2 pattern disappears, and the clause is more straightforward

So after når, at, fordi, hvis, etc., you usually get normal subject-verb order.

Teksten means the text.
The definite ending -en is attached to the noun:

• en tekst = a text
• teksten = the text

Using teksten suggests a specific text is meant, probably one already known from the context.

If the meaning were more general, Danish might use something else, for example:

• en tekst = a text
• tekster = texts

But here, teksten points to a particular text.

Here bedre is modifying the verb forstår. It means better, as in understand better.

So the structure is:

• jeg forstår teksten bedre = I understand the text better

Placing bedre after the object is very normal in Danish.

Also note that bedre is the comparative form of godt when used adverbially:

• godt = well
• bedre = better

So this is not describing teksten. It is describing how well the text is understood.

No, it is functioning as an adverb here.

Compare:

• en bedre tekst = a better text
  Here bedre describes the noun tekst, so it acts like an adjective.

• jeg forstår teksten bedre = I understand the text better
  Here bedre describes the verb forstår, so it is adverbial.

That distinction is very useful in Danish.

Because Danish often uses the present tense for:

• current states
• general truths
• repeated situations
• situations that are expected to happen

So:

• Jeg føler mig mere selvsikker = a present state
• når jeg forstår teksten bedre = a general or recurring situation

English does something similar:

• I feel more confident when I understand the text better

Even though the idea may include future occasions, present tense is still natural.

Yes, but it changes the nuance a little.

• Jeg føler mig mere selvsikker = I feel more confident
  Focuses on your inner experience.

• Jeg bliver mere selvsikker = I become / get more confident
  Focuses more on a change or development.

So the original sentence is about how you experience yourself, while bliver would emphasize growing confidence.

Yes.

The infinitive is:

• at forstå = to understand

The present tense is:

• jeg forstår = I understand

This is a very common Danish verb, and in the present tense it does not add -er in spelling the way many verbs do. Its present form is simply forstår.

Yes, depending on context.

In this sentence, når can suggest either:

• when I understand the text better
• whenever I understand the text better

Because the sentence expresses a general relationship, many learners will hear a whenever sense in it, even if the natural English translation uses when.

That is very normal with når.