Hun overser feilen.

Hun is the subject form of she, so it is used because she is the one doing the action.

• hun = she
• henne = her

In Hun overser feilen, hun is the subject of the sentence.

Overser is the present tense of the verb å overse.

So the pattern is:

• å overse = to overlook / fail to notice / ignore
• overser = overlooks / is overlooking

In this sentence, Hun overser feilen means She overlooks the mistake or She fails to notice the mistake.

No, and this is an important false friend.

In English, to oversee often means to supervise.
In Norwegian, å overse usually means to overlook, miss, or fail to notice something.

So:

• English oversee = supervise
• Norwegian overse = overlook / fail to notice

They look similar, but they do not usually mean the same thing.

Because feilen is the definite singular form of feil.

• en feil = a mistake / an error
• feilen = the mistake / the error

Norwegian often puts definiteness at the end of the noun as a suffix.

So feilen literally contains the idea of the.

In Norwegian, the definite article is often attached to the noun itself.

So instead of saying a separate word like English the mistake, Norwegian says:

• feilen

This -en ending shows that the noun is definite.

In Bokmål, feil is usually treated as a common gender noun:

• en feil = a mistake
• feilen = the mistake

The ending -en is the usual definite singular ending for many common gender nouns.

The word order is the standard Norwegian pattern:

Subject + Verb + Object

• Hun = subject
• overser = verb
• feilen = object

So:

• Hun overser feilen.
• She overlooks the mistake.

This is the normal order in a simple main clause.

Usually, no. That meaning is more often expressed with ser over as two words.

This is a very useful distinction:

• å overse = to overlook / fail to notice
• å se over = to look over / review / check

So:

• Hun overser feilen = She fails to notice the mistake.
• Hun ser over feilen would sound more like she is looking over or checking it, depending on context.

The past tense of å overse is overså.

So:

• Hun overser feilen. = She overlooks the mistake.
• Hun overså feilen. = She overlooked the mistake.

This is an irregular verb, so the past form is not something simple like overse-te.

You usually put ikke after the verb in a main clause:

• Hun overser ikke feilen.

That means She does not overlook the mistake.

Depending on context, a more natural sentence might also be:

• Hun ser ikke feilen. = She does not see the mistake.

These are close, but not always identical:

• ikke overse = not overlook / not ignore / not miss
• ikke se = not see

Yes. Feil can mean both mistake and error, depending on context.

So Hun overser feilen could also be understood as:

• She overlooks the error

The best English choice depends on what kind of situation you are talking about.

They are different both in meaning and in how they are grouped.

• overser is one verb
• ser over is a verb + adverb/preposition combination

A learner should pay attention to the fact that Norwegian often changes meaning depending on whether something is written as one word or two words. Here, that difference is very important:

• overser = overlooks
• ser over = looks over / reviews

Yes, sometimes. Å overse can mean either:

• fail to notice something, or
• ignore something

The exact meaning depends on context.

So Hun overser feilen could mean:

• she does not notice the mistake, or
• she notices it but chooses to ignore it

Without more context, both are possible.