Final answer:
The symbol represents a switch, which can open or close a circuit to control the flow of current.
Step-by-step explanation:
In a circuit diagram, the symbol in question represents a switch. A switch is a device that can open or close a circuit, controlling the flow of current. When the switch is closed, the circuit is complete and current can flow through the circuit. When the switch is open, the circuit is broken and no current can flow.