I can't understand
Lo siento pero no puedo entender lo que ha dicho en inglés.
I'm sorry, but I can't understand what you've said in English.
No puedo entender lo que usted dice.
I can't understand what you're saying.
Hablas tan bajo que no puedo entender lo que dices.
You speak so softly that I can't understand what you're saying.
No puedo entender sus ideas para nada.
I can't understand his ideas at all.
No puedo entender nada de lo que dices.
I can't understand anything you're saying.
Casi no puedo entender lo que dice.
I can barely understand what he's saying.
No puedo entender lo que pasó.
I can't understand what happened.