Okay kiddo, so a commando mortar is like a big, fancy gun that shoots explosives up into the air and far away. But instead of needing a whole bunch of people to use it safely, a commando mortar only needs one person to set it up and fire it.
Now, the way this works is that the person using the commando mortar will first pick a spot to aim it at, like a group of bad guys that they want to attack. Then they will put the mortar on the ground and load it up with the explosives, kind of like putting bullets in a gun.
Once it's all loaded up, the person using the commando mortar will aim it at the bad guys and then pull a trigger to make it shoot. When they do this, the explosives inside the mortar will shoot up into the air and fly towards their target.
Now, why is this so special for commandos? Well, because commandos are usually out in the field all by themselves or with only a small group of friends. So having a weapon like a commando mortar means they can still attack enemies from a distance, even when they don't have a big team of people with them. Does that make sense, kiddo?