The idea is to speed processing of security lines, keep slower passengers from holding up the line and reduce the amount of manual work by TSA officers to move bins back to the front of the line.
This primer will give you a head start on how it works:
Using the new automated security lanes at the South checkpoint
Step 1: Once you get to the screening area, approach one of the five stations and take a loading bin from beneath the station.
Step 2: Fill it with all your items, including a roll-aboard suitcase, for example. The bins are 25 percent larger. (But here's one hint: Oversized carry-on luggage won't fit in the bin.)
Step 3: Push the bin onto a conveyor belt, which will move it into the X-ray machine, then walk through the checkpoint. You don't have to wait for the person in front of you to finish. Each bin has an RFID radio frequency identification chip for tracking.
Step 4: Retrieve your belongings on the other side of the X-ray machine. Your bin is automatically returned to the front of the line via a lower-level conveyor belt. If a bin's contents needs to be manually screened, it is bumped over to an alternate conveyor belt for an officer's inspection.