any here know electricity or an electrician?

[BERNIE MOSFET]

Based on the wire color, BBC. The red and black legs are hot, each with 120 volts out of phase. The ground and neutral should read almost the same, except for the voltage drop along the neutral.
The thing that I've never clearly understood with commercial ac is the phase differences (single, 2, 3) and how they affect the voltages. Wouldn't the example they give be a 2-phase circuit? Each 120V leg being a phase?

In the case of single, or 2-phase, 240 VAC line voltage has a peak voltage around 340 V. For 3-phase it is about 415 V. The difference being sqrt(2) vs sqrt(3), which are derived from how the RMS values are calculated - more specifically it has to do with power calculations, which is why we care about RMS values to begin with. I can try to explain the math behind it later if you want.

3phase is preferential because of better energy efficiency.