A view of an Asteroid Belt, one of two kinds of Asteroid Field.
Erratic Debris is an 'area' effect that affects an entire gravity well, namely those that contain Asteroid Belts.
The effect of this ability is simple - it decreases the accuracy of all ships with weapons within the gravity well by 20%. It is unclear as to whether this merely decreases the damage output by 20%, or if 20% of all forms of ordinance miss.
Seemingly, only the Akkan's Targeting Uplink ability counters the effects of Erratic Debris, meaning a fleet supported with an Akkan class in an asteroid field is quite a bit more formidable than might appear.