You will receive it immediately after you have passed, for an additional fee of between R37 and R126, depending on what province you are in. See the Government Services site used to provide a breakdown of costs by province, but they no longer supply one. Your best option for determining the cost of your licencing fee is to contact your local driving licence testing cetre. Another option is to contact a local driving school or instructor who deals with your local driving licence testing centre - they will generally be aware of what the current costs are. They are subject to change without notice though, so you may always want to bring a little bit of extra money with you just in case.
As of 2010, your licence will be valid for 24 months (2 years) from date of issue. After that, it will expire, and if you wish to persue a Driver's Licence, you will need to reapply and rewrite the Learner's Test.