What is the purpose of serous fluid in regards to wound healing?

Why it occurs? Part of the body's response to a wound is the release of chemicals from inflammatory cells that cause the fine blood vessels (capillaries) to leak fluid from the blood stream. This allows certain elements in the blood to fight infection and also allows for easier healing. We often use dressings to keep a wound moist, so it is an adaptive response. Can also mean infection, so see MD if question.
Wound healing. Much of the fluid from wounds are byproducts of the healing process. There is no real role in the healing process. Too much drainage can slow down healing due to the moisture levels and the enzymes.