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

Here is Why You Need An Adapter

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

Namibia

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

Type D

Type M

Brazil

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

Type C

Type N