When you have fulfilled all obligations in terms of your IVA i.e. paid all contributions/complied with your Supervisor, then you will be discharged from any debt incurred prior to the IVA being approved by creditors. Any remaining unsecured debt (other than those excluded) in your IVA will be written off.
Your Supervisor will carry out the required statutory procedures to conclude your IVA and you will then be formally discharged from your IVA.