Okay kiddo, you know how when you're in a car and it goes over a bumpy road, you can feel it bouncing up and down, side to side? Well, big boats in the water feel the same way, and we call it "ship motions".
There are three main types of ship motions: rolling, pitching, and heaving. Imagine a big boat sitting in the water. If it starts to roll, that means it's tipping back and forth from side to side, kind of like a see-saw. This can happen because of waves or wind hitting the sides of the boat.
Pitching is when the boat tips forward and back, like a ride on a roller coaster. This happens because of waves hitting the front or back of the boat.
Heaving is a bit harder to explain, but it's when the whole boat moves up and down with the waves. It's kind of like floating up and down in a pool.
All of these ship motions can make people on board feel a little bit seasick, or like they're on a roller coaster. It's important for the captain and crew to be aware of these motions so they can keep everyone safe and make sure the boat stays stable and balanced.