All the physical components of a computer like processor, hard drives, graphics card, memory; this includes personal computers, phones, or any electronic devices. The term is predominately used by enthusiast who build their own computers and frequently swap out parts and upgrade. To get a better idea I would recommend checking out /r/hardware on Reddit to see more examples and discussions.
Computer hardware is advanced electronics made up of mostly silicon and metals. Motherboards, memory, and graphics cards use printed circuit boards. A printed circuit boards (PCB) is usually green and physically supports the components attached to it. Components are solder onto the printed circuit board. Lines are printed on the board that electrically connect components. You’ll also find capacitors, transistors, resistors, diodes, and chips on the PCB.
In the same way you go to Home Depot to buy building supplies or hardware to construct or maintain a house, computer hardware is used to build a computer. A computer case does have quite a few screws in it! You have to screw the motherboard down to the case. Also, hard drives are generally screwed in or attached to rails and slide in. Besides using a screw driver, that is where the commonalities between computer hardware and Home Depot hardware end.