Mining in the context of the military means placing explosives or other devices underground or underwater to destroy or hinder enemy movement.
Imagine you are playing a game of hide-and-seek with your friends. You know your friend likes to come through a certain part of the playground, but you don't want them to catch you. So, you hide something under the ground that can make a loud noise and scare your friend away from that area.
In a similar way, soldiers sometimes want to stop their enemies from coming into certain places or moving in certain ways. So, they bury explosive devices in the ground or plant them underwater where their enemies might go. When the enemies get close to these devices, they will explode and create a big boom that can hurt or scare them away. This is called mining.
The soldiers who do this have to be very careful when they place the explosives, because they don't want to accidentally hurt their own troops or innocent people who might be nearby. So, they use special tools to make sure they put the explosives in the right place and at the right depth.
Mining can be a very dangerous job because the soldiers doing it have to go close to the enemy's territory and work in secret. But it can also be very helpful for the military because it can prevent the enemy from moving around as freely and might even give their own troops an advantage in battle.