A reflection is a flip over a line: The reflected image is the same size and shape as the original image and each point in the reflected image is at the same distance to the line of reflection as the original corresponding point. Everyday objects such as mirrors and calm waters produce reflected images that are examples of this kind of isometry.
A rotation means a turn around a fixed center point of a certain fixed angle. The distance from the center to any point on the shape stays the same. Every point is mapped to a place on an arc of a circle about the fixed center. If you look at a merry-go-round, you will see rotations of objects. A rotation of 90°, for example, would map a figure to a place one fourth around a circle. A rotation of 360° would result in the figure in the same place it started.
A translation is a movement by “sliding.” See the examples below of vertical and horizontal. Can you think of translations that would be both vertical and horizontal?