"To grill the pineapple" means to cook or barbecue the pineapple slices on a grill or an open flame, usually to enhance its flavor or create a smoky taste. Full definition
Serve with grilled pineapple slices, and sprinkle with mint. (myrecipes.com)
I have a recipe for grilled pineapple salsa for you tomorrow — perfect balance of sweet and heat — can't wait to have it on my chicken tacos for lunch today. (mybizzykitchen.com)
To make the salsa, grill the pineapple slices or heat in a pan for 5 to 10 minutes until the pineapple is browned. (fieryfoodscentral.com)