There are many possibilities:
http://help.sap.com => BASIS (may be you need to search for your specific “Operating System” and Database)
for Books go to official documentation at
The following may be good start:
The ABAP Beginner’s 2-pack for programers ABAP or
The Beginner’s Complete Collection
For Basis certification you need to know at least an Operating System like:
Windows Server, IBM AIX, HPUX, Solaris, or Linux
and an Database like:
Oracle, DB2, MaxDB, or MS-SQL
together with SAP-Basis Applikation: netweaver
additional knowledge of: Solution Manager is also needed.
For your best starting point, you should know the needed combination of your company/customer,
Good Luck and welcome to the SAP comunity:
There is lot of materials are available on net for the Basis download R/3 Handbook it is very useful.