I've been a computer systems designer from circuitry to software through several generations of technology for 45 years. I use the word "hacking" more broadly than hack5. It means "finding and creating ways to do things that are novel and not really what was expected by the original designer (of hardware, software, chip, part or just a thing)". Obviously to do that you need to be really lucky and stumble into something or know a lot and/or learn more.
The mindset of hacking can be used to do bad things to people and systems. It can also be used to prevent others from doing bad things by 'heading them off at the pass'.
To broaden the thinking, here is an example: Many hardware systems use a bus protocol called I2C. I2C is used by motherboards to communicate with their flash memories. If there is a motherboard password, it's stored in that part, in clear text actually. Similarly, it may use I2C to communicate with the keyboard interface. Using a device sold by "Dangerous Prototypes" not Hak5, one can manipulate I2C, intercept communications with the flash memory and gain access to the BIOS that was not intended (or someone forgot the password). All this requires some soldering of course, to create the connections to the Bus Pirate.
There are also ways of using transistors, diodes, etc that really are not in their specs but, by pushing the specs can be used in special ways. This too is hacking to me.
Bending a coat hanger into a tool to snag something, pull a wire through or whatever - that too is hacking the coat hanger. Making a rocket out of PCB pipe for fuel - that's also hacking.
There are as many types of hacking as there are hackers that are truly creative and knowledgeable. The range for a hacker is more than operating and computer systems. It's physics.
The more you learn, the more intuition you will have. Have fun. Don't hurt nice people, help them (or not)