What does fall off mean at sea?

In nautical terms, "falling off" refers to the situation where a sailing vessel loses headway, or its motion through the water decreases significantly, due to a change in wind direction or a loss of wind pressure. This can occur when the vessel is no longer able to maintain a course into the wind, causing it to drift or fall off in a different direction. To prevent falling off, sailors must adjust the sails or change the boat's heading to regain control and maintain the desired course.