Connector Header Through Hole 2 position

What is the use of PCB header?

Pin headers are widely used in PCB circuit boards buile-up printed board electrical appliances, and meters. Their role is to function as a bridge between blocked or isolated circuits in the circuit and take on the task of current or signal transmission. Usually used in conjunction with the female header to form a Cable Connectors I/O Connectors connection; or used in conjunction with an originality electronics  IC  terminal to form a board-to-wire connection; it can also be used independently for board-to-board connection.