You need an embassy visa for Namibia if you have an Algerian passport
Visa options for Namibia
Electronic visitor visa for Tourism
Travellers need a visa to visit Namibia for Tourism. A Namibian eVisa is the fastest and easiest way of obtaining a visa for Namibia because travellers can submit their application and supporting documents online. Once the application is approved, travellers receive their eVisa confirmation electronically. A valid visa is required to board the flight. If the visa is expired or doesn’t match the traveller’s passport information, travellers will not be able to board their flight.