Phase Angle:

Phase angle is the fraction of a cycle, in degrees, which has gone through because a voltage or current has passed by a given value.  The given value is generally zero.  Referring back to Figure, take point 1 as the beginning point or zero phase.  The phase at Point 2 is 30°; Point 3 is 60°, Point 4 is 90°, and many more, until Point 13 where the phase is 360°, or zero.  A word more generally used is phase difference. The phase difference could be used to define two different voltages which have the similar frequency, that pass by zero values in the similar direction at different times. Within Figure, the angles along the axis denote the phases of voltages e₁ and e₂ at any point in time.   At 120°, e₁ passes by the zero value, that is 60° ahead of e₂ (e₂ equals zero at 180°).  A voltage e₁ is said to lead e₂ through 60 electrical degrees, or it could be said in which e₂ lags e₁ through 60 electrical degrees.

Figure: Phase Relationship

Phase difference is also used to compare two various currents or a current and a voltage. Two voltages, or a voltage and a current is zero degrees if the phase difference among two currents, they are said to be "in-phase." they are said to be "out-of-phase" if the phase difference is an amount other than zero.