"Dipped beam" is an English (United Kingdom) colloquial term equivalent to what we call "low beam" in the USA.
As the weather becomes colder, the voltage regulator built into the alternator attempts to compensate by increasing the battery charge voltage. This stresses the light bulbs, with the result that Volvos have a marked tendency for bulb failures during the winter. I have to change one or both low beam headlights every winter, and keep extras in the spare tire well.
I don't expect the lights to recover when the weather improves.
Changing the bulbs will eliminate the error messages, as should adding some washer fluid to the reservior. The bulbs are user-replaceable, and available at auto parts stores, as well as Wal-mart. The headlight capsule, type H7, may be a little hard to find. Instructions for access and changing should be in your owner's manual.
Do not touch the headlight bulb with you bare hands, as the oils from your skin will greatly reduce service life. No similar restriction applies to the brake light bulb.