A dive or blast is an in-game movement executed by football players. It looks like it sounds, a player jumps forward in a falling motion, "diving" towards the ground. The dive is done in a scenario where the ball carrier finds it likely that he will be sacked or pushed out of bounds and feels the need to maximize yard gain. It allows players to quickly travel a short distance. A player needs to weigh whether it is worth it to dive or not since after a dive the play is interrupted and the attacking team can't advance anymore.
Diving is commonly done when a short distance needs to be traveled, regardless of that being to achieve a first down, or to enter the end zone and score a touchdown. In those cases, coaches can draw plays where the ball carrier dives right after getting the ball, travelling the needed distance without much risk of losing the ball. The dive can be done with blocking from the linemen or simply by jumping over other players. A good dive can be a game changer, scoring the winning touchdown in a 4th and 1, or taking a team to a much needed first down.