If a blood electrification unit puts out 150ua then it is outputting .000150 amps. Resistance is that which 'resists' the flow of electrons. The unit of measure is ohms. People that are mineral deficient have more resistance to current flow and therefore have to apply more voltage to get the same amount of current as a normal person. The output control on many units is just a variable resistor that causes a greater resistance to current flow as the knob is turned counterclockwise.
Frequency is the rate of waveform repitition.
Waveform is the 'form' of the voltage waveshape being output by a unit. A squarewave is the normal waveshape for most electromedicine devices. Pulsed DC changes voltage from zero to a positive voltage and back to zero according to the frequency rate. AC changes voltage from positive to negative and back to positive according to the frequency rate. So an AC Rife unit can be said to output 30 volts peak, or 60 volts peak to peak.