Final answer:
If you don't understand something in Spanish, you can say 'no entiendo' or 'repita, por favor' to ask for clarification.
Step-by-step explanation:
If someone says something to you and you don't understand, you can say 'no entiendo' which means 'I don't understand' in Spanish. Another option is to say 'repita, por favor', which means 'repeat, please'. If you want to express that you understand a little, you can say 'un poco'. The other options, 'de nada' and 'hable', are not appropriate replies in this context.
Learn more about Understanding and responding in Spanish conversations