Here are some ways to respond, depending on the situation:
If you know Pablo's friend:
* "El amigo de Pablo es [nombre del amigo]." (Pablo's friend is [friend's name].)
* "Su amigo es [nombre del amigo]." (His friend is [friend's name].)
If you don't know Pablo's friend:
* "No lo sé." (I don't know.)
* "¿Quién es su amigo?" (Who is his friend?)
* "No tengo esa información." (I don't have that information.)
If there's more context:
* You could ask for clarification: "¿A qué amigo te refieres?" (Which friend are you referring to?)
* You could offer a guess: "¿Es [nombre del amigo]?" (Is it [friend's name]?)
Remember to use the appropriate pronoun for Pablo (he, his, etc.) based on the context.