A ballistic shield is a big shield that police officers or soldiers use to protect themselves from guns or bullets. It's like a giant piece of metal or plastic that they can hold in front of them to stop bullets from hitting them. Think of it like a really big, heavy shield a knight might use when they fight in a battle.
This shield is made of special materials that are very strong and can stop bullets from hurting the person behind it. The shield is also designed to be lightweight enough so that the person holding it can move around easily while still being protected.
When the police or soldiers are going into a dangerous situation where they know there might be gunfire or someone shooting at them, they use a ballistic shield as a way to keep themselves safe while they do their job.
So even though they can't see through the shield like a window, they can feel safe knowing that they are protected from harm.