my assumption:
you have a electronic product which cannot be physically connect o the earth-so u use a chassis ground.
Now we have a Digital ground which is connected to a digital circuit and hence exposed to high speed switching which can cause EMI. This has to be prevented to go to the other digital circuits connected to the same digital gnd.
The cap offers very low impedance in high frequency and bypasses all the signal to chassis gnd and hence interference bet's digital circuits is prevented.
At zero frequency, the cap is open- but still you digital ground has to be connected to the chassis. Hence the resistor....