The javelin throw is when someone throws a long stick called a javelin. Think of it like throwing a really big pencil, but instead of aiming at a piece of paper, they're throwing it as far as they can. People do this as a sport and it takes a lot of practice to get really good at it.
The person throwing the javelin usually runs up to a line and then throws it over their shoulder, trying to get it to go really far. The javelin can go really high up in the air and travel a far distance before landing on the ground.
It's important to make sure that nobody is standing in the way of where the javelin will land because it could cause them to get hurt. The people watching stand behind a safety line to make sure they're a safe distance away.
The person who throws the javelin the farthest distance is the winner of the competition!