The Essentials: Voltage, Current, Resistance
These are the foundations of electronics. Search YouTube/Google if you are unsure of them.
Having a solid understand of electronics basics sets the foundation for what you can learn in terms of PCB design.
I would recommend at least understanding these terms/concepts before continuing:
- Circuits (open vs closed)
- Switches (and what they do as an electrical component in general)
- Voltage (V), Current (I), Resistance (R)
- Ohm’s Law (V = IR)
- Resistors
- AC Power vs DC Power
- Electric circuit diagrams
Continue:
Diodes