Reactive Power (negative P)
You have transcribed your quote incorrectly. It says "power is being returned from the load". What you have said in your question is nonsense. The actual text is describing situations when the load is a reactive component. Under these circumstances current and voltage may be up to 90 degrees different in phase and if you multiplied the voltage and current you would see both negative and positive sections of power.

Note that if the phase angle is exactly 90 degrees (perfect C or L) the positive power and negative power are exactly equal meaning average power is zero: -



Scenario 1 is a resistive load and scenario 3 is a purely reactive load (an inductor as it happens)