The more you learn about electricity, the more you realize that it's hard to explain.
Still, here's a very basic description of how electricity works.
It's important because the signal in any cable is just a series of electrical impulses.
The easiest way to understand electricity is to think of it like water.
When you turn on the tap, the amount of water you get is dependent on the size of the spigot, the size of the water pump, and whether or not you have a clogged screen at the end of the faucet.
There are a lot of terms but we'll concentrate on the ones that really matter to a electric power cable.
Volts, simply put, are what pushes the water.
Ohms are a measure of resistance, that is to say how well something flows through something else.
Something with a higher resistance will be harder for electricity to flow through.
Current is a measure of "the big picture."
How much electricity is actually flowing?
It's measured in amps.
Parts of a cable like the dielectric have capacitance which is roughly like a sponge placed inside a pipe.
Something with capacitance temporarily stores current and gives it back later.
Because nothing is perfect, not water pipes or coaxial cables, there is always loss.
Loss happens all the time, but obviously there is more loss as cables get longer.
Cables, as well as other parts of the system, have their losses measured in decibels or dB for short.
If you add more water to a system, that's gain.
Same thing with electricity.
A positive gain is a negative loss, and a positive loss is a negative gain.
An amplifier adds electricity to a system and introduces gain.
The signal inside your power cables is measured in volts.
Changing those voltages by a tiny little bit is what makes it possible to carry information.
Everything that carries electricity has an impedance measured in ohms.
For residential systems, everything has an impedance of 75 ohms.
If impedances don't match up, electricity can get "backed up" and this can cause all sorts of problems.
Looking at a power cable, you should know how much loss it has over the length you want to use it.