You Do Need power plug adapter while traveling from Estonia 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 Estonia are C and F. This is how they look like.

Estonia

In Estonia, outlets of type C and F are in use.

Type C

Type F

South Africa

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

Type C

Type M

Type N