Load factor is the number of Gs the aircraft structure is supporting. In unaccelerated flight it’s 1. Straight and level, an established climb, and an established descent are all unaccelerated.

In a turn, an airplane experiences a higher load factor as a function of the bank angle. The lift from the wings is what makes the airplane turn. Since some of the lift is being diverted to the horizontal, the total lift must be increased to keep the airplane from sinking. The result is a higher load due to the acceleration in the turn.

The beginning of a climb or descent also changes load, but once established, the load returns to 1.