A stabilizer is like a special part that helps a big boat or ship not tip over in the water. You know how sometimes you balance on one foot and if you don't keep your body straight, you might fall to the side? Well, a big boat can do the same thing if it doesn't have something to keep it steady.
Inside the ship, there are long fins or wings that stick out into the water. These fins can move up and down, back and forth to help balance the ship. Like when you put your arms out to the side for balance, the fins on a ship help keep it from leaning too much on one side.
So, when the wind or waves start to push against the boat, the stabilizers move to help keep the ship steady. They also make it easier for the captain to steer the ship and keep it on course. It's kind of like a superhero power for ships that keeps them from falling down in the water.