It represents a conductor in a circuit.
What is a conductor?
Conductors themselves aren't typically shown with specific symbols. Instead, their presence is indicated by straight lines connecting various components in the diagram.
Different types of connections between these lines may have specific markers for clarity:
Crossing wires: Shown with a small half-circle "bridge" to indicate they don't touch.
Joined wires: Connected with a small dot or circle at the junction.
Importance:
Conductors are essential components of any functioning circuit. Without them, the current wouldn't be able to flow, and the circuit wouldn't operate.
The choice of conductor material depends on factors like the required current carrying capacity, cost, and flexibility.