Pandehåret er blevet for langt.

It means the fringe in British English or the bangs in American English.

Literally:

• pande = forehead
• hår = hair

So pandehår is literally forehead hair.

Because Danish usually adds the definite article to the end of the noun.

So:

• et pandehår = a fringe / a set of bangs
• pandehåret = the fringe / the bangs

The ending -et is the definite ending for a neuter noun.

In Danish, it is normally treated as a singular neuter noun, even though English often says bangs, which is plural.

That is why the sentence uses:

• er = singular is
• langt = the neuter singular form of long

So Danish thinks of it more like fringe hair or the fringe than like a plural noun.

Because pandehår is a neuter noun.

In Danish, adjectives agree with the noun:

• common gender singular: lang
• neuter singular: langt
• plural/definite: lange

Here, pandehåret is neuter singular, so the adjective is langt.

Compare:

• Bilen er lang. = The car is long.
• Håret er langt. = The hair is long.

Here it is an adjective, not an adverb.

It describes pandehåret, so it agrees with that noun:

• Pandehåret er langt.

It may look like an adverb to an English speaker, but in this sentence it is an adjective used after er.

Here for means too, not English for.

So:

• for langt = too long
• meget langt = very long

That is an important difference:

• meget langt = long, and perhaps impressively so
• for langt = longer than wanted or appropriate

Er blevet is the perfect tense of blive, which often means become or get.

So:

• er blevet for langt = has become too long / has gotten too long

The sentence is talking about a change over time: it was acceptable before, but now it is too long.

Because blive normally forms its perfect tense with er.

So the correct form is:

• er blevet

This is similar to how some other Germanic languages use be with verbs of change or movement. In this sentence, blive expresses a change of state, so er blevet is the normal form.

Danish often uses the definite form where English might prefer a possessive in context.

So:

• Pandehåret er blevet for langt. can naturally mean My bangs have gotten too long, if it is obvious whose fringe is being talked about.
• Mit pandehår er blevet for langt. is also possible, and it makes the ownership explicit.

The version without mit sounds natural if the context already makes it clear.

It is a normal Danish main clause:

• Pandehåret = subject
• er = finite verb
• blevet = past participle
• for langt = complement

So the structure is basically:

subject + verb + participle + complement

Nothing unusual is happening with the word order here. It is a straightforward statement.

You could, but it loses the idea of change.

• Pandehåret er for langt. = The bangs are too long.
• Pandehåret er blevet for langt. = The bangs have become too long / have gotten too long

So er blevet adds the sense that they were not too long before, but now they are.