what dose "action"，"effector_translation" and "effector_target_translation" mean?

"action": "description": "An action representing a 2D delta cartesian setpoint for the robot."
"effector_translation": "description": "The current end effector translation as a 2D cartesian coordinate."
"effector_target_translation": "description": "The target location for the end effector as a 2D cartesian setpoint."

Hi, thanks for your great job!
The description of the dataset is pretty ambigous for me. What do ”cartesian setpoint for the robot“, "end effector translation " and "location for the end effector " mean? Are they describe the same thing (robot arm end effector)?

Thanks for your attention and I am waiting for your kind response.