This is the 1634th most frequent German word.
welcher
"Welcher" means "which" in English.
Here, 'welcher' is used as an interrogative pronoun to ask about a specific item from a group (movies in this case).
Welcher Film läuft heute im Kino?
Which movie is playing in the cinema today?
'Welches' acts as a relative pronoun here, linking the clause 'ich gestern gelesen habe' to the noun 'Buch'.
Das Buch, welches ich gestern gelesen habe, war sehr spannend.
The book, which I read yesterday, was very thrilling.
In this sentence, 'welches' is employed as an interrogative pronoun within indirect speech to inquire about a choice between two options.