Compatibility summary
Your South Africa plug may fit in Republic of the Congo outlets, as both use at least one common plug type.
Plug comparison
South Africa plug types: C D M N
Republic of the Congo plug types: C E
Both countries share at least one plug type (C D M N and C E), so some plugs may work without an adapter. Check your appliance.
Voltage comparison
South Africa: 230V, 50Hz
Republic of the Congo: 230V, 50Hz
Voltage difference is within a range many devices tolerate; check your appliance label.