With this OIC you get to bare your soul and say "I did it! I owe it! But I cant pay in this life time or in two life times. Woo I feel better ! NOW that I got that off my chest."
Actually it is a little less dramatic than that. If you owe a tax and there is not enough time left on the statute of limitations to pay it, you could qualify for this offer. There are some circumstances that could disqualify you—namely assets that could be liquidated. Also, if you have a high enough monthly income the IRS feels you could pay enough of a payment. They will look at these first by doing a full financial investigation. This will include documentation proving your monthly income, assets, and liabilities.
To have a chance at the OIC do not attempt to put this information together on form 433 by yourself. This is a common mistake of your "do it yourself people". The IRS loves this but you will not like the outcome. Seek out a professional tax resolution firm.