This is the 73rd most frequent Swedish word.
vilket
"Vilket" means "which" or "that" in English, depending on context.
In this sentence, 'vilket' is used as a relative pronoun meaning 'which' to specify a noun.
Jag vet inte vilket hus du menar.
I do not know which house you are referring to.
Here, 'vilket' serves as a conjunction introducing a relative clause and linking it to the main clause.
Filmen var spännande, vilket jag inte förväntade mig.
The movie was exciting, which I did not expect.
Here, 'vilket' is used as an exclamation meaning 'what a' in English.