You Do Need power plug adapter while traveling from Belize to Guinea-Bissau.

Here is Why You Need An Adapter

The outlet and plug type used in Guinea-Bissau is C and in Belize are A, B and G. This is how they look like.

Belize

In Belize, outlets of type A, B and G are in use.

Type A

Type B

Type G

Guinea-Bissau

In Guinea-Bissau, outlets of type C are in use.

Type C