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

Here is Why You Need An Adapter

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

Serbia

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

Type C

Type F

Uruguay

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

Type C

Type F

Type L