Spanish phrase
Te agradecería ~.
Meaning
I'd appreciate it if you ___.
When to use it
Polite way to ask for a favor. It frames the request as appreciated ahead of time to soften the request and reduce pressure on the listener.
Example dialogue
Te agradecería que me llamaras mañana.
I'd appreciate it if you called me tomorrow.
Perfecto, te llamo a las diez.
Perfect, I'll call you at ten.