Radio silence is like playing hide and seek but with radios. When soldiers are in a war or on a mission, they need to communicate with each other using radios. But sometimes, they need to be very quiet and not talk on the radios. This is called radio silence. It's like being really quiet so no one hears you.
When soldiers are in radio silence, they use hand signals or special codes to communicate with each other. This is important because if they talk on the radio, the enemy might hear them and know where they are or what they are doing.
Just like when you play hide and seek, you don't want the person who is seeking you to know where you are hiding. So, soldiers have to be very quiet and use other ways of communicating when they are in radio silence.