Very basically , a purely resistive load supplied by an AC voltage consumes power (volts x amps) without changing the relative phase of the voltage and current sine wave forms thus it represents a unity power factor , or power factor of 1. Inductive loads , like motors , lighting ballasts (they have a choke which is an inductor) etc change the relative phase between voltage and current , so for a given load power they consume more current to achieve the rated power of the motor. Practically , that means the actual power consumed is more than the power the meter will read. This is a power factor of less than 1. Utility companies provide supply on an assumption of a power factor of no less than 0.95 , but a consumer with lots of electric motors will have a factor of around 0.7 so they will a/ be charged on a higher tariff as they actually consume more power than a standard meter reads and b/ will need a larger capacity service connection to cope with the current.
So , on start up the current surge of a large induction motor is massive because the inductance value of that motor before it starts to turn is very large , this means the resistance the supply see's is almost a short circuit. To handle that start surge without power factor correction would need a massive supply rating. To reduce this surge a capacitor is placed across the supply which cancels out some that surge by bringing the phase of the voltage and current sine waves closer together. The value of that capacitor has to be calculated using all relative factors.
This is why you will see motors rated in KVA.
Difficult to simplify a very complicated subject !