This is the 73rd most frequent Swedish word.
vilket
"Vilket" means "which" or "that" in English, depending on context.
Here, 'vilket' is used as an exclamation meaning 'what a' in English.
Vilket vackert väder vi har idag!
What beautiful weather we have today!
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.