This article in The Conversation is by prominent scholar Roger Southall:

South Africa adopted its electoral system during the process of making a new constitution in the run up to its transition to democracy in 1994.

The system agreed was proportional representation. This involved parties drawing up lists of representatives which would get seats in legislatures according to the proportion of votes the parties won in the polls. This system was chosen because it was seen as allowing maximum representation of different political opinions and ethnic identities.

The system has worked well to represent minority parties along with recurrent African National Congress majorities in the National Assembly and in most of the country’s nine provinces.

Find the full story here.