Charleze Theron had to learned to speak English fluently in her teens I think? She moved to Johanessburg for school if I remember correctly. Most South Africans I know grew up speaking English though, but I think certain parts of the country use Afrikaans as their primary language and might not be fluent in English.

There are a few Jellies who lived or live in South Africa, so hopefully they see the Q.

All of the Afrikaaners that I’ve met speak English fluently, but then, I met them in the United States, so there’s a filter.

According to a family member that went to SA on business, all of the locals he met/came in contact with were bilingual.

yes

No. I know several where English is a second language

According to this, about 50% of Afrikaans speakers understand English. Your question asks about speaking English well, which is a higher standard that understanding, so I would conclude that most Afrikaans speakers do not speak English well.

I lived in S. Africa in the 70’s, and there were lots of Afrikaans-speaking people in the more rural areas whose English was pretty rough. Either way, Afrikaans-speaking people have pride in their culture, and would always appreciate a translation in their own language, even if they could make it out in English.