1. 1.9 the meaning and importance of belief in Islamic teaching on holy books other than the Quran.

2. The Zabur, Injil, and Tawrat
This was a collection of hymns and songs which Muslims believe was used for worshipping in Solomon's temple in Jerusalem. They believe that many of these were written by Dawud (David). Some scholars equate this back to the biblical book of psalms.
This was the revelation received by Isa (Jesus). Some scholar's equate this to the four Gospels of the Christian bible, although this is debated.
This was given by Allah to the prophet musa(Moses). Many people equate this to the Jewish torah or the 5 books of moses from the Christian bible.

3. The importance of this belief.
they demonstrate that Allah cares for people because Allah revealed His message directly to people over time.
Although the message distorted, the originals were revelations from Allah and therefor should be respected