German phrase
Warum möchten Sie ~?
Meaning
Why would you like to ___?
When to use it
It asks someone's reason. This formal question politely asks why they want to do something.
Example dialogue
Warum möchten Sie an diesem Kurs teilnehmen?
Why would you like to attend this course?
Ich möchte meine Sprachkenntnisse verbessern.
I would like to improve my language skills.