The weight of a part. This also effect the proportions of your robot. Mass distribution is key to maintaining a stable center of mass and a functional robot. The mass and proportions of a robot will also effect it's Base Speed.
Center Of Mass
The center of mass is the location where your robot's mass is centered around, ie where your robot would balance from. The location of your center of mass is key to maintaining a stable and functional robot. In edit mode, your press "Center Of Mass" key ('O' by default) to toggle the display of your robot's Center Of Mass.
The base HP of a part. The total HP of your bot is the sum of this attribute of all parts on your bot. This is boosted according to the percentage of Health Boost.
A base moving speed attribute belonging to a movement cube. If there's only one kind of movement cube on your bot, the final base moving speed of it will be the same as one belonging to that kind of movement cube. Otherwise, it will be between all of kinds of movement cube on your bot. Currently, the highest Base Speed in game is 260 (mph).
This is boosted according to the percentage of Speed Boost.
Hover Blades will make your bot hover. During a fight, you can press "Move Up" key ('Space' by default) to increase hover height and "Move Down" key ('Left Shift' by default) to decrease it. In case that it's "hover", there's a cap of hover height, of course, indicated by "Max Hover Height" attribute.
Some kinds of movement cube have this attribute, which indicate how much Mass they can carry. In general, your will find that all kinds of movement cube won't performing as expected if you only put a few of them on your bot if it is very heavy. However, this phenomenon is extremely evident on all kinds of movement cubes that have this attribute. Maybe you will find it's fine if you only made movement cube having this attribute overload a little bit, but if you continue, it will be almost disabled instead of only not performing well. (Hover Blades can't hover, planes can't take off... etc.)