Learn Danish: Han barberer sig skaldet. - He shaves his head bald.

In this sentence, skaldet (bald) is an objective predicative. This means it describes the state of the object (sig) as a result of the action, rather than describing how the action was done. He doesn't shave in a 'bald way'; he shaves himself so that he becomes bald.

Does skaldet have to agree with sig in gender and number?

Yes! An objective predicative must match the object it describes. Here, sig refers back to Han (he), which is singular, so we use the singular form skaldet. If the subject were plural, like 'De barberer sig' (They shave themselves), the adjective would take the plural form skaldede.

Why does skaldet end in '-et' if it is describing a common gender word like Han?

It looks like a neuter ending, but skaldet is actually the base dictionary form of the word. It originates from a past participle. Because the base word naturally ends in '-et', it does not change or drop the '-et' when describing a common gender word like Han or sig.

Why does the Danish sentence use sig (himself) instead of translating 'his head'?

While an English speaker naturally says 'shaves his head', Danish often prefers using the reflexive pronoun sig combined with an adjective to express this. You are literally saying 'He shaves himself bald.' Using sit hoved (his own head) is possible, but sig skaldet is a very common and natural phrasing.