To keep it simple; the Load Factor is the ratio between aircraft weight and wing lift.
The other way around; wing loading can be determined as a function of load factor and weight.
In normal straight-and-level, unaccelerated flight, load factor is 1, i.e. lift equals weight. Vertical acceleration, as experienced when changing rate of climb/descent, or in level turns, would change the load factor. The LF can also be measured with an accelerometer parallell to the aircrafts vertical axis.