Automation framework is a process that helps test engineers control the tool operations for a complete and correct test execution of the automation scripts on the build.

In short it describes the directory structure of how the files are stored.

Framework varies from one automation tool to another.

For example for Mercury Interactive tools in Windows environment

the framework for WR :
C:\Program Files\Mercury Interactive\WR\tmp\
C:\Program Files\Mercury Interactive\WR\tmp\\chklist\list.ckl
C:\Program Files\Mercury Interactive\WR\tmp\\exp\gui1
C:\Program Files\Mercury Interactive\WR\tmp\\default.xls
C:\Program Files\Mercury Interactive\WR\tmp\\msqr1.sql

the framework for QTP :
C:\Program Files\Mercury Interactive\QTP\tests\