The correct answer to this open question is the following.
The negative effect that the lockdown had on South Africa's economic growth is that it not only has stopped the growth in South Africa, but it had also diminished it.
The pandemic has forced people to lockdown. When people are not out there on teh street, this means that there are no people to enter the stores, restaurants, shops, and many retail shops. No clients, no money.
This has created havoc in the economy because many shops and businesses have closed. The direct impact on unemployment. People had lost their jobs. No income also means they cannot afford to buy other things or invest in entertainment, impacting other industries in South Africa.
The lockdown also has affected tourism. There is no tourist in South Africa taking the photo-safaris tours. And tourism is a great generator of money in South Africa.
In simpler terms, the economy of South Africa has plumbed. And let's remember that before the pandemic, South Africa already had a series of economic problems and a lot of poor people, mostly black people.