The concept of Roll-Pitch-Yaw specifically refers to the movement of aircraft among its axes. In addition these concepts are terms used in the field of Robot Mechanics / Kinematics. Let’s define these terms in aviation.
First, let’s explain the Roll term. Roll literally means rolling, lying down. The term of roll refers to the movement among Longitudinal Axis. As can be seen from the figure, if we draw a straight line from the nose to the tail of the aircraft, we can call it the Z axis. The plane rotates around this line, that is, the wings move up and down. The movements of the aircraft around the roll axis are controlled by the parts like Aileron and Spoiler. We can see them clearly in the Figure.
Second, let’s explain the concept of Pitch. Pitch literally means pitching motion. Pitch concept refers to movement among Lateral Axis (Horizontal Axis). To understand this concept more clearly, if we examine the Shape, let’s assume that we draw a straight line from tip of one wing of the plane to the tip of another wing. This line becomes our X axis. The rotation of the plane around this line is also called the pitching motion. This corresponds to the Pitch concept. In other words, it is the up and down movement of the nose and tail of the aircraft. The movements of the aircraft around the Pitch axis are controlled by the Elevator as can be seen clearly from the figure.
Finally, let’s explain the concept of Yaw. Yaw literally means going off course, turning to the right and left. Yaw concept refers to Vertical Axis. To understand this concept more clearly, if we examine the shape again, let’s assume that we draw a line extending from the upper part of the body to the lower part of the plane passing through the center of gravity. This line becomes our Y axis. The rotation of the plane around this line is also called Yaw (Rotation) motion. In other words, we can say that the nose and wing of the plane move left and right. The movements of the aircraft around the Yaw axis are provided by the Rudder (Direction Steering) as can be seen clearly from the figure.
Below is the figure where you can see the parts of an airplane in general.