To be honest, I've never seen this brand of coffee before, but I'd bet that if I asked my parents they would remember it from many years ago... possibly before I was even born!
The word "Raadsaal" means "Council Hall" if you translate it directly... which I guess is an odd name for a brand of coffee. Strangely, if you zoom in you'll be able to read that the manufacturer of this traditional-Afrikaans-sounding coffee brand is an old British company, "Brooke Bond Tea & Coffee Co".
This aside, the funniest part of this poster is the phrase "Sterk Koffie!", which means "Strong Coffee!". If you zoom in you'll notice that the coffee consists of 62.5% chicory and only 37.5% real coffee... which, in my opinion, isn't very strong at all! :)