From Sony:
What are "orbs"?
If specs of dust particles are floating in the air when you're taking a picture, they can be illuminated by the light of the flash and sometimes appear in the image as white, round glare spots, also known as "orbs". This symptom tends to occur in low-light environments when using a compact digital camera because of the proximity of the flash to the lens assembly. It is not a malfunction.
From Wikipedia:
In
photography,
backscatter (also called
near-camera reflection[1]) is an
optical phenomenon resulting in typically circular
artifacts on an image, due to the camera's
flash being reflected from
unfocused motes of
dust, water
droplets, or other
particles in the
air or water. It is especially common with modern
compact and ultra-compact digital cameras.
[2][3]

A hypothetical underwater instance with two conditions in which circular photographic artifacts are likely (A) and unlikely (B), depending on whether the aspect of
particles facing the lens are directly
reflect the flash, as shown. Elements are not shown to scale.
Caused by the
backscatter of light by unfocused particles, these artifacts are also sometimes called
orbs, referring to a common
paranormal claim. Some appear with trails, suggesting
motion.
[4]