Okay kiddo, so let me explain to you what BLUF means in communication. BLUF stands for "Bottom Line Up Front." It means that when you want to tell someone something important, you should put the most important information first, so the person can understand it quickly.
For example, let's say you want to tell your friend about a really fun day you had at the park. You could say "Hey, I had a great time at the park today! We went on the swings, played frisbee and had a picnic!" That's a long way to tell them about it, right? A BLUF version would be "I had so much fun at the park today! We did lots of fun things like swinging, playing frisbee, and having a picnic." Much simpler and straight to the point!
In short, BLUF means to put the most important thing you want to say first, so the person listening can understand it quickly and easily.