This circuit clamps current that's above 5.6V.
Sometimes it is desirable to limit the range of a signal (prevent it from exceeding certain voltage limits) somewhere in a circuit.This circuit will accomplish this. The diode prevents the output from exceeding about +5.6V; with also no effect on voltages less than that (including negative voltage)
The only limitation is that the input must not go so negative that the reverse breakdown voltage of the diode is exceeded.
The series resistor limits current during clamping action; however, a side effect is that it adds 10kOhm of series resistance to the signal, so it's a compromise between maintaining a desirable low source resistance and a desirable low clamping current.
