Bridge rectifier still putting out ac and dc, why?
The output is probably unfiltered pulsating DC so you'll get some kind of a measurement on the AC range of a multimeter. It doesn't really mean much. The DC measurement will be the average voltage.
The apparent AC reading is related to the AC component, adjusted to appear RMS for a sine wave (it isn't a sine wave). So it's kind of meaningless for most purposes. Diagram below from here

A quick measurement at my desk gives about 6VAC apparent AC voltage with a 17VDC average voltage (unfiltered full-wave rectified), using such a meter, which fits well with your measurement.