The DPF (diesel particulate filter) warning light indicates either a problem or regeneration of the particulate filter. You should drive and keep a steady speed in an rpm range of 2000 - 2600rpm for at least 15 minutes or until the regeneration of the filter is complete. When it's done, the symbol disappears. Otherwise, you need to go to the service center asap.

You may encounter the regeneration of the filter when you frequently use your diesel car for short distances.