Howzit. (That's as far as I'm going to go with phonetic representation of my accent.)
The South African accent(*) is flatter than the standard English accent, with variations on vowel sounds.
For example, the short "a" sound comes across as a short "e", so: South African = Seouth Effrican. In some regional accents, "Sexy Eyes" can sound like "Sexy Ar*e", which is mildly amusing
Then there's a similarity with the New Zealand way of pronouncing short "i". Phonetically it is represented as the upside-down "e", and is a flat sound. My English aunt couldn't understand me when I asked for milk unless I mimicked her pronunciation.
I tend to speak in a less-flat accent, mainly because I have family from the UK and it was drilled in that we should open our mouths when we speak.
I'm a good mimic with a lot of accents, local and international. German, English, Cockney, Glaswegian, Greek, Russian, French, Australian, etc.
US and Canada accents are harder, and I end up sounding like a strangled Australian.
Edit: Charlize Theron changed her accent completely to get work in Hollywood. She only sounds local when she speaks in her native Afrikaans (which is a derivation of old Dutch, but more gutteral). Arnold Vosloo (the original Mummy in the Brendan Fraser film of the same name) has not changed his accent much since he's worked in Hollywood.
(*) I must apologise for not mentioning that white people only comprise about 9% of the South African population, so I was speaking of the white South African accent. Black South Africans sound completely different, as English is often a third or fourth language to them. English may be the de facto language of the country, but it is only one of the eleven official languages. The two biggest languages for mother-tongue speakers are Xhosa and Zulu (**), with a number of our citizens able to speak as many as seven languages. White South Africans tend more to speak only two: English and Afrikaans.
(**) Nelson Mandela is a native Xhosa speaker. The current president, Jacob Zuma, is a Zulu speaker.
_________________
If you break a crumb in half, you have two crumbs - George Carlin