Okay, kiddo, let me explain the concept of filament propagation in a way that you can easily understand.
Imagine a train track that is covered in snow. A train wants to pass through this track, but it cannot because the track is covered in snow. However, there is a special machine that can clear the snow off the track, making it possible for the train to pass through.
In a similar way, filament propagation is like that special machine clearing the snow off the train track. Filaments are tiny, thin threads made out of plastic that are used in 3D printing. When you use a 3D printer, the filament needs to pass through a tube or a nozzle to create the object you want.
But what happens when there is a clog or jam in that tube or nozzle? That's where filament propagation comes in. The printer will automatically try to clear the clog by pushing more filament through the tube or nozzle. This is like the special machine clearing the snow off the train track - it's making a path for the filament to pass through so it can continue 3D printing.
Overall, filament propagation is just a mechanism that helps keep your 3D printer working smoothly, similar to how the special snow-clearing machine keeps the train track clear for the train to pass through.