嘿 I found the question!
Delailah: How does dumbledore understand parseltongue?
J.K. Rowling: Dumbledore understood Mermish, Gobbledegook and Parseltongue. The man was brilliant.
So Dumbledore can understand Parseltongue fine but she does not clarify whether he can speak it.
link Here's the link with the Q & A I 发布 above. :)