You Do Need power plug adapter while traveling from Swaziland to Uruguay.

Here is Why You Need An Adapter

The outlet and plug type used in Uruguay are C, F and L and in Swaziland is M. This is how they look like.

Swaziland

In Swaziland, outlets of type M are in use.

Type M

Uruguay

In Uruguay, outlets of type C, F and L are in use.

Type C

Type F

Type L