To create a dimension table for Country from your source data, you need to perform these two actions34:
Delete the City column. You don't need this column for your Country dimension, as it is not a descriptive attribute of Country. You can create another dimension table for City if you want to use it in your analysis.
Remove duplicates from the Country column. You want to have a list of unique countries in your dimension table, so you need to remove any duplicate values from this column.