A Wingman is a friend of you, in best case an experienced PUA that helps you by gaming in a group of woman. His main function is entertaining the friends, so that they don’t cockblock your interaction with the target. He should know which girl you choose as the target and only talk with her to tell good things about you (DHV).
Wingwoman or Winggirl
The same principle but it’s often easier especially if she is pretty, that gives you really high value and she can easily open and introduce you to new girls.