A roll out in football is a designed play in which the quarterback receives the ball and begins moving towards one side of the field. A right-handed quarterback usually rolls out to the right side, while a left-handed quarterback usually rolls out to the left side in order to make for easier throws based on the player's strong hand.
Roll outs often involve overloading one side of the field to the same side in which the quarterback is moving towards. For example, if the quarterback is moving towards his right prior to making a pass attempt, the play will likely call for the receivers to run routes that ultimately land them on the right side of the field. This is done in order to overwhelm the defense by having several potential options for the quarterback to throw to on the same side of the field. Roll outs also help quarterbacks evade blitzes (the defense sends extra players after the quarterback rather than dropping the normal amount of players into coverage) by alreading requiring them to be running in one direction, giving them a head start over pursuing defenders.