Burst Mode enables your camera to capture several photos at one trigger with specified intervals between shots. This function can be handy when using PIR in order to identify what caused its triggering.
Sometimes a photo can be blurry and the object in the photo can be poorly identified. It happens for example if triggering was caused by a movement of a person: one may stand with one’s back to the camera or the person’s image may be blurred and therefore impossible to identify. Burst Mode lets the camera take several photos and send them to you. It increases the likelihood that the object in the photo will be identified.
Using Burst Mode affects the power consumption of the camera and increases data transfer time.