You Do Need power plug adapter while traveling from Brazil to Namibia.

Here is Why You Need An Adapter

The outlet and plug type used in Namibia are D and M and in Brazil are C and N. This is how they look like.

Brazil

In Brazil, outlets of type C and N are in use.

Type C

Type N

Namibia

In Namibia, outlets of type D and M are in use.

Type D

Type M