Spreadsheet Ranger, I think you are referring to Google Adsense, and not Adwords. Adsense is placed on your website and you get paid when visitors click on ads. Adwords is the advertising platform where you advertise on other websites to drive traffic.
Here is my experience:
Is there a lot of money to be made with Adsense?
Yes, but only if you have a website with a lot of traffic. On average, less than 7% of visitors will click on an ad. I have a website that gets around 5000 unique visitors a day from search engine results. I get hundreds of thousands of page views a day. I make around R3k a month from this website alone in Adsense. Some months it may be less and others a bit more. Around 2-3% of my visitors clicks on ads.
There are indeed large international websites making hundreds of thousands of Dollars a month, but they get hundreds of millions or even billions of visitors and page views.
Can you make a living on Adsense alone?
No, you need to look at other ways to monetize your website. Things like paid membership options or selling products too.
Driving traffic to your website
Every person who wants to run a website must spend a lot of time and money to drive traffic. This is where Adwords come in. You will need to spend money to advertise your website, and Adwords is probably the best source to do it. Unfortunately, it is expensive.
There are a number of other ways you can drive traffic, but they all demand a lot time, work and probably money too.
South African traffic enough?
Unfortunately no. If your target market is South Africans alone, I am afraid to say that you will never make a lot of money with Adsense. You need to focus on driving international traffic to your site too. This may often require change of domain names as they play a big role in SEO.