Dynamic range is like the difference between whispering and shouting. Imagine you are talking to your friend and you start talking really quietly. Then you get louder and louder until you are yelling. That's a big dynamic range in your voice.
In music, dynamic range is the difference between the softest and loudest parts of a song. So, if a song starts out quiet with just a guitar and then a chorus comes in with big drums, that is a big dynamic range.
When people talk about dynamic range, they are usually talking about how much detail you can hear in a recording or performance. If a recording has a big dynamic range, you can hear all the little details in the quiet parts and all the big sounds in the loud parts.
But sometimes a recording or performance doesn't have a big dynamic range. Everything sounds the same volume and there aren't any quiet or loud parts. This is like if you talked to your friend in a monotone voice and never changed your volume or tone.
So, dynamic range is like the difference between whispering and shouting or between a soft guitar and a loud drum. It's what makes music interesting and helps you hear all the details.