buffing time

[Boyd]

Yes, derekf is correct - DA is a short way of saying (D)ual (A)ction sander.

Production shops (shops that do mostly collision repair) use a DA sander to speed up the sanding and buffing process.

Most custom shops recommend to NEVER use a DA. Like Frank says, it will pigtail. Or worse yet, a DA sander in the hands of someone inexperienced will cut through the clear very quicly - especially near panel edges or on body lines.