The flag of South Africa was adopted on April 27, 1994, the day the country held its first democratic elections. It has six colors and a Y-shaped band that converges at the hoist.
A flag designed to be temporary
The old flag was inseparable from apartheid, and replacing it before the election was not optional. What followed was a national public competition, then a scramble: the final design came from Frederick G. Brownell, then State Herald, and it was adopted as an interim flag with the expectation that something more considered would follow.
Nothing did. The interim flag was popular immediately and was simply kept.
Six colors and no official meanings
Black, yellow, green, white, red, and blue. The green Y starts at the flagpole and splits into a horizontal band running to the fly, a shape read as convergence: separate paths joining and continuing together.
The government has never assigned official meanings to the colors, which was a deliberate choice in 1994 and remains a useful one. People read them anyway. Black, yellow, and green are the colors of the African National Congress, whose flag clearly influenced the design. Red, white, and blue come from the Dutch Prince's Flag and the British colonial inheritance. Putting both sets on one field, without explaining what either means, is the whole argument of the flag.
Protocol
The flag is used at official and public events and represents the country abroad. It should be raised briskly and lowered ceremonially, must not touch the ground, and must not be used as a tablecloth, a curtain, or anything else of that kind. It is a fixture at sports events, diplomatic missions, and public celebrations.
Where it sits among other flags
Its closest relatives are the ANC flag and the Dutch Prince's Flag, both of which fed directly into the design. More loosely, it belongs to a group of post-colonial national flags adopted at the moment of a political break, where the job of the design was to signal that the previous order was over.
Alongside the flag, the national coat of arms carries part of the same load in representing South African identity.
References
[1] South African Government Handbook (https://www.gov.za/)
[2] International Federation of Vexillological Associations (http://www.vexillology.org/)
[3] Publications by Frederick G. Brownell