Can anyone let me know what exactly is the work of a PMO accelerator ?
The PMO Accelerator add-in is a collection of content and view configurations designed for project portfolio management not tied to any specific industry. The PMO Accelerator provides a collection of CA Clarity PPM ready content that your organization does not have to create. The add-in enables you to support the existing program management office (PMO) operations. The add-in is useful for managing and gaining insight into portfolio, program, and project performance.
The following included in the add-in:
For more information, please go through the documentation available on the support site
As Chandrani has mentioned, it adds additional configuration to save you the effort of doing it!
it's also a prerequisite for the solution pack, which is worth having in place.
Note that once you install an add-in you cannot uninstall it!