Okay kiddo, have you ever played a game with your friends where you take turns drawing something and the others have to guess what it is? That's kind of like what "draw by agreement" is.
When people need to make plans or come up with ideas for something, they might use "draw by agreement" to visualize what they're talking about. It works like this: instead of just saying what they're thinking, they draw it on a piece of paper or a whiteboard. Then, everyone who's involved in the discussion takes turns suggesting changes to the drawing so that everyone is happy with what's being proposed.
It's like a little game where everyone tries to make the drawing better by adding their own ideas. The great thing about "draw by agreement" is that it helps everyone to understand what's being talked about more clearly. Plus, it's a lot of fun!