It means someone actually driving your car and making adjustments to your tune while monitoring different parameters as opposed to calling zip or intense etc and getting an off the shelf tune.
This. It's different from just ordering a generic mail order tune like ZZP etc where they just doing adjustment that may have worked on other cars.. A in car tune will be tuned to your car specifically. So adjustments can be made
Squirrels are my engine. I need a Ford Regal
04 Comp G.