These are the wet pads for the Braava 200 series of robot mops from iRobot. Meaning, when one of these pads is on the mop it will spray more water on the floor and make more passe of the room. Basically, it is the pad that will make the robot do the deepest cleaning job. There is a bit of a scented solution of some kind on the bottom of the pad that gives off a scent as the robot mops up the water. I am not sure if it contributes anything more than that, however.
The mop knows which type of pad is attached based on the perforations in the "card" (for those old enough to remember the punch cards that were used for computer programming years ago, it is like that) that slips into the base of the mop to attach the pad. It is akin to a Swiffer dusting sheet. Depending on how large a room you are mopping you may have to use more than one pad and one cleaning cycle to get the entire room clean. You do want to make sure that if there any bigger lint balls or more than just a minimal amount of dust or dirt on the floor, that you use a vacuum and/or a dry pad (which is like a Swiffer sheet), otherwise this will just push them around. These are best used if your floor just needs relatively light cleaning (for example, if you clean them once or twice a week on a regular basis) or in relatively low-traffic areas that have a hard surface floor.