You Do Need power plug adapter while traveling from Brazil to South Africa.

Here is Why You Need An Adapter

The outlet and plug type used in South Africa are C, M and N and in Brazil are C and N. This is how they look like.

Brazil

In Brazil, outlets of type C and N are in use.

Type C

Type N

South Africa

In South Africa, outlets of type C, M and N are in use.

Type C

Type M

Type N