The ROBS transaction involves taking a qualified retirement account (usually a 401K), distributing funds from it in a ROLLOVER to buy the stock of a new C corporation.  

Here's the basics as I understand them:

A C corporation is established

A C corp sponsored retirement account is established

Funds from the taxpayer's previously existing qualified 401K are rolled over into the new C corp plan.

Funds are distributed from the new C corp plan to purchase the corporation's stock.

There are other specifics that go into this - amendments that have to be written and then changed for HCE and 5500 requirements, but that's the basics. 

The purpose is to use the funds from an existing qualified account, distributed them tax-free through the rollover, and for the corp plan to be the holder of the c corp shares.