Does a South African citizen travelling from Canada to South Africa via Amsterdam, with a lay over of 23:50 need a transit visa?
According to Which visa do I need to travel to the Netherlands?, citizens of South Africa do not require a transit visa to change planes in Amsterdam.
However, you would need a regular Schengen visa if you would like to leave the airport. 23 hours is quite a long time to stay within the airport. It's certainly possible, but not very interesting.