What does hitting the "antennas" signify?

Hitting the antennas signifies that the ball is out of play. In volleyball, the antennas are vertical markers attached to the net that help define the boundaries of the playing area. If a ball touches an antenna, it indicates that the ball has crossed outside the designated width of the net, thus rendering it out of bounds. This rule helps maintain the fair play aspect of the game as it clearly delineates the area where the ball must pass in order to remain in play.