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