What do you understand from this?
What do you get from this?
I just wanted to add that there's a difference between these expressions depending upon the context.
For me, "What do you understand from this?" asks for an intellectual or factual response.
In the question "What do you get from this?", the "get" can mean either "understand" or "receive" and could additionally ask for an emotional response.
Q: "What do you get [understand] from this?"
A: "I get [understand] that the author of this book was sad."
Q: "What do you get [receive] from this?"
A: "I get [receive] a sense of sadness when I read this book."