VISITORS VISA  

Visitors’ visas are for international travelers (citizens of other countries) who have permanent residence outside South Africa and who wish to visit the country on a temporary basis for tourism or business purposes for a period of 90 days or less.

A visa simply indicates that your application has been reviewed at a South African embassy, mission or consulate and that the consular officer has determined that you are eligible to enter the country for a specific purpose.

The visa will allow you to travel to a South African port of entry where an immigration official will then determine if you are allowed to enter South Africa and for how long you can stay for that particular visit. Visitors are restricted to the activity or reason for which their visas were issued. Any foreign visitor entering South Africa must have a valid passport for the duration of their stay, and all visitors must comply with the conditions of their visas. 

As of March 2020 Citizens of 133 countries coming to South Africa for tourism purposes including Hong Kong, Singapore, Australia, New Zealand, Canada, USA, UK and almost all European nations don't require a visa and will be granted permission for short-term stay upon arrival.

Please refer to the below list for visa exempt countries.
http://www.dha.gov.za/index.php/immigration-services/exempt-countries

Visitors from outside these 133 countries must apply for a visa in advance. .
Even if you are a citizen of a country that doesn't require a visa, make sure to check the official rules for South Africa visa requirements as they can periodically change.