A blunt shape means the tip and tail of the board are short and squared off rather than tapering to a point. This design cuts down on swing weight—the resistance you feel when spinning—making it noticeably easier to rotate off jumps and onto rails. That's why you'll see blunt shapes on most park and freestyle boards.
The trade-off is that you lose some effective edge length and float in deeper snow, since there's less surface area at the contacts. Blunt shapes are also built tougher, handling rail impacts better than a thin, pointed tip that could get damaged. If you're spending most of your time in the park, street riding, or just hitting features, a blunt shape is a smart match. For all-mountain or powder-focused riders, a pointed or slightly rounded shape will serve you better overall.