Spatchcocked chicken is splayed or butterflied. It’s done this way so it cooks faster or can be cooked on a grill. It’s also easier to eat than a whole roasted chicken.
Place chicken, breast side down, on a work surface. Starting at thigh end, cut along 1 side of backbone with kitchen shears. Turn chicken around; cut along other side. Discard backbone or save for stock. Flip chicken, and open it like a book. Press firmly on breastbone to flatten.