There are many different cultures in Namibia, from German-speaking farmers to indigenous Himba, Damara, Herero, and San tribes.
In the major cities, people tend to be open and friendly and the general culture will be familiar to anyone from Europe or North America. If you want to visit one of the indigenous tribes, there are various ‘living museums’ across Namibia, for example the Damara living museum near Twyfelfontein. These take the form of ‘mock villages’ which are run by local communities to show visitors what life used to be like, and to some extent, is still like in their society.
For a more authentic experience it’s best to contact the local lodges in the area and see if they can organise a guide. A guide will be able to instruct you on any cultural nuances and can arrange a ‘real’ village visit without disturbing the community.