You have a source table with 21 rows. You want to add a column. In the end you'll still have 21 rows.
The "expected" table has 18 rows. So with only adding a column you will never get there, it's just impossible.
To get the expected output though, you can do this easily: just create a table with just Pais
as values and PowerBI will automatically group. See here a (more minimal) example:

PS. If you wanted to add a column -say- with the number of years the country appears in the source data, you should:
- choose the matrix visualization
- add "Pais" (country) for rows
- add e.g. "Ano" (year) for values, and summarize by "Count (Distinct)"
[País]
column to a chart it will automatically group the vales in distinct ones, I don't find a reason for do that in a calculated column. - alejandro zuleta