You Do Need power plug adapter while traveling from Czech Republic 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 Czech Republic are C and E. This is how they look like.

Czech Republic

In Czech Republic, outlets of type C and E are in use.

Type C

Type E

South Africa

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

Type C

Type M

Type N