What are some methods to understand electricity?

Question

in other words what are the names for the tools that

electricians and scientist use to mesure the voltage and current, the amps resistance and power?

Answer 1

The above list is great but don't forget the oscilloscope.  It shows electrical potentials that vary over time such as a sine wave, frequency modulated (FM) waves, Amplitude modulated (AM).

Answer 2

volt meters

ammeters

ohmmeters

(the combination of these is called a multimeter)

high voltage probes