So imagine you are playing a game of pretend with your friends, and you all decided to play army. You each have toy guns and you pretend to fight battles. Now imagine if one of your friends took it really seriously and started training every day, wearing special camouflage clothing, and making plans to attack other people. That friend would be acting like a paramilitary.
A paramilitary is a group of people who act like an army but are not actually part of the official military. They might use similar tactics and weapons as soldiers, but they don't have the same legal authority to use force. Sometimes paramilitary groups form to protect their community or fight for a cause they believe in, but other times they can be dangerous and cause harm to others. It's important to remember that only official military members have the legal authority to use force and kill people.