What is pcd
PCD (Pitch Circle Diameter) is the diameter of the circle formed from all the studs or wheel rim holes.
What is center bore
Centerbore is an opening on the back of the wheel that is machined to exactly match the hub, centering the wheel on the vehicle properly. If the wheel is a vehicle model-specific, it will have been bored to match the one vehicle. If the wheel is meant to fit multiple vehicles, a centering ring system will be used to match the desired specifications of the hub of the vehicle, maintaining position so that the lugs can be torqued down.
What is offset
Offset is the distance, in millimeters, between the centerline of the wheel and the hub mounting surface. There are 3 types of offset: zero offset, positive offset, and negative offset. Zero offset is when the hub mounting surface is in line with the centerline. A positive offset is when the hub mounting surface is further towards the outside of the wheel, with the negative offset being the opposite, with the hub mounting surface being towards the inside of the wheel.