What voltage and amps are and why high volts may not kill you but high amps will
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If it helps, think of voltage as the “desire” for electricity to get from one place to another, and amps as how much work we can make that electricity do along the way.
High voltage will try really hard to get from where it starts to where it wants to go. (This is a simplification, bordering on inaccurate, but it is a way to visualize it.) Low voltage will move, but will not try as hard. On a side note, this is why we use high voltage to move electricity long distances.
Amps are what we use to do work. A 2 amp light will be much brighter than a 1 amp light, at the same voltage. If something happens, and the available number of amps drops to 0.5 amps, then those lights will go dim (and the 2 amp light might not shine at all).
High voltage is a concern because it can go through the human body, where lower voltage would not. The human body has enough resistance that voltages from normal batteries, as you would find in a cell phone, or a petrol-powered (not electric) car, will not pass through the body. Household voltage will, and things that use higher voltage (such as neon or fluorescent lights) will pass through a body even easier. High voltage can also pass through water and other things that are not obvious conductors, and can jump through the air (think of lightning or a Van de Graaff generator, or even just static electricity from rubbing your feet on carpet).
Amps are what does the “work” though. High voltage with no amps behind it will give you a zap or tingle (think of a Taser/stun gun, or electrified fence). With amps, you can weld metal together, burn wood, use a pickle as a light source, or cook meat/flesh. (Or, obviously, do useful work such as produce light, turn motors, power appliances, and run electronics.)
However, high voltage and low amps can still be dangerous in some situations, since the heart uses low amp power to control its beat, and the right/wrong kind of shock across the heart needs to only have a few hundredths of an amp (tens of milliamps) to make the heart stop beating or to keep it from being able to beat correctly.
Meanwhile, low voltage and high amps is not typically dangerous directly. A standard petrol car’s battery provides hundreds of amps, up to a thousand amps. It is completely safe to touch both terminals with your bare hands though. At the same time, there can still be a danger if you touch a piece of metal to both terminals, but that is due to sparks (which can cause fires), heat (enough to burn fingers and such), or explosion (if the battery overheats from discharging too quickly).
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