Breakdown of Würdest du bitte die Lampe einschalten?
du
you (informal singular)
bitte
please
die Lampe
the lamp
würde
would (conditional auxiliary)
Questions & Answers about Würdest du bitte die Lampe einschalten?
Why is the verb "würdest" at the beginning of the sentence?
Because this is a yes/no question. Just like in English, the conjugated verb comes first. Here, würdest acts as the helping verb, so it takes the very first position.
"Einschalten" is a separable verb. Why isn't the "ein" separated here?
Because würdest is acting like a modal verb in this sentence. When you use würdest for polite requests, it pushes the main verb to the very end of the sentence in its full, unseparated dictionary form (einschalten).
How would this sentence change if I wanted to be more direct and just tell someone to turn on the lamp?
You would drop würdest and use the imperative (command) form. For du, it would be: Schalt bitte die Lampe ein! Notice how the separable verb splits when it is the main conjugated verb of the sentence.
Could I use "könntest" instead of "würdest" here?
Yes! Könntest du bitte die Lampe einschalten? means "Could you please turn on the lamp?". Both könntest (could) and würdest (would) are perfectly correct and very common for polite requests in German.