As it says, a patch repair is normally when there is a patch in a wall, ceiling or other plastered surface that requires a plaster repair.
The initial step is to remove any remaining loose or flaking plaster,or defected plasterboard. This is normally done by using a cold chisel and a ball pein hammer to chip away the loose or flaking plaster or plasterboard.This may make the area requiring a patch larger,but will give a cleaner area to work on and a better and more secure finish overall.
Once the area is clean, it can then be prepared for the plaster to be applied. This can vary depending on the size and depth of patch repair required.