Provision is a component of the Aegir hosting system.
Ægir is a new set of contributed modules for Drupal that aims to solve the problem of managing a large number of Drupal sites. It does this by providing you with a simple Drupal based hosting front end for your entire network of sites. To deploy a new site you simply have to create a new Site node. To backup or upgrade sites, you simply manage your site nodes as you would any other node.
The provision component of this system provides the backend used for system level tasks such as creating configuration files and managing databases and backup files.
For more information on the system, and the other components, please take a look at the Aegir overview wiki page
For install instructions, see the INSTALL.txt provided in the distribution or the documentation wiki.