Learn Swedish: Klär de på sig sent? - Do they get dressed late?

In Swedish, getting dressed is expressed with a two-part verb, klär på (literally "clothes on"), combined with a reflexive pronoun. Here, the pronoun is sig (themselves). So the phrase literally means "clothes on themselves".

Why do we use sig here instead of dem?

Sig is the reflexive pronoun for all third-person subjects, including de (they). Because the subject de is performing the action on themselves, we must use sig. If you used dem, it would mean they are dressing a different group of people!

How is the subject de pronounced in this sentence?

Just like in most everyday Swedish, the word de (they) is pronounced like dom. So you will hear "Klär dom på sig sent?" when people speak naturally.

Why does the word for late (sent) end with a "t"?

Sent is acting as an adverb here, meaning it describes the action of getting dressed. In Swedish, you usually create an adverb by taking the basic adjective, which is sen (late), and adding a "-t" to the end.