Ilden brenner.

Because ilden is the definite singular form of ild.

• ild = fire / a fire
• ilden = the fire

In Norwegian, the definite article is usually added to the end of the noun as a suffix, instead of being a separate word like the in English.

So:

• en ild = a fire
• ilden = the fire

The ending -en marks a definite singular noun for many masculine nouns in Norwegian.

Here, ild is commonly treated as a masculine noun:

• en ild
• ilden

This is a very common pattern in Norwegian:

• en bil → bilen
• en hund → hunden
• en dag → dagen

So -en works like the in English, but attached to the noun.

brenner is the present tense of the verb å brenne.

So:

• å brenne = infinitive
• brenner = present tense

This form is used for:

• I burn
• you burn
• he/she/it burns
• we burn
• they burn

Norwegian verbs do not change for person the way English verbs do. The same present-tense form is used with all subjects.

Examples:

• Jeg brenner
• Du brenner
• Ilden brenner

Yes. The infinitive marker is usually å.

So the full infinitive is:

• å brenne = to burn

In the sentence Ilden brenner, the verb is already conjugated, so you do not use å there.

Compare:

• Å brenne er farlig. = To burn is dangerous.
• Ilden brenner. = present-tense statement

This is the normal Norwegian word order for a basic statement:

subject + verb

So:

• Ilden = subject
• brenner = verb

That makes Ilden brenner a very standard simple sentence.

Norwegian usually follows verb-second word order in main clauses, but in a plain statement with the subject first, that often looks just like English:

• Ilden brenner
• Barnet sover
• Mannen kommer

Yes. Å brenne can cover several related ideas, depending on context.

It can mean:

• to burn
• to be burning
• sometimes to burn something or to burn up, depending on how it is used

In Ilden brenner, it means that the fire is actively burning.

This is common in Norwegian: one verb may cover meanings that English expresses with slightly different phrasing.

A rough pronunciation guide for an English speaker is:

• Ilden ≈ ILL-den
• brenner ≈ BREN-ner

A few helpful notes:

• ld in ild can be a little tricky; in careful speech you may hear the d weakly.
• The r in brenner is pronounced, but how it sounds depends on dialect.
• The e in brenner is a short vowel.

If you want a simple learner-friendly approximation:

• ILL-den BREN-ner

In standard Bokmål, ild is commonly used as a masculine noun:

• en ild
• ilden

Some Norwegian nouns can vary by dialect or style, and Norwegian in general allows some flexibility with gender in certain cases, but for a learner, en ild / ilden is the safe form to learn.

Usually ild most naturally means fire, not specifically flame.

If you want to talk about a flame, Norwegian often uses:

• flamme = flame
• flammen = the flame

So:

• Ilden brenner is best understood as the fire is burning
• Flammen brenner would be closer to the flame is burning

That said, context always matters, and ild can sometimes be used more broadly in poetic or figurative language.

Yes, grammatically you can say En ild brenner.

That means a fire is burning.

The difference is:

• En ild brenner = indefinite, introducing a fire
• Ilden brenner = definite, referring to a specific fire already known or understood

So the choice between en ild and ilden depends on context, not on the verb.

Ilden brenner is natural Bokmål.

In Nynorsk, you would more typically see:

• Elden brenn

The biggest differences here are:

• ilden → elden
• brenner → brenn

So if you are studying Bokmål, Ilden brenner is the form to focus on.