def country_to_continent(country_name):country_alpha2 = pc.country_name_to_country_alpha2(country_name)country_continent_code = pc.country_alpha2_to_continent_code(country_alpha2)country_continent_name = pc.convert_continent_code_to_continent_name(country_continent_code)return country_continent_name
countries = list(df['country'])[country_to_continent(country)for country in countries] 

def country_to_continent(country_name):country_alpha2 = pc.country_name_to_country_alpha2(country_name)country_continent_code = pc.country_alpha2_to_continent_code(country_alpha2)country_continent_name = pc.convert_continent_code_to_continent_name(country_continent_code)return country_continent_namecountry_name = list(df['country'])
country_to_continent(country_name)

Acutually I can't get it why my second one is wrong but the first one is right . and get unhashable error

In the second snippet, you pass list of countries to country_to_continent function, which according to the first example, receives a single country as a parameter.

If you want to convert the whole column in your Dataframe, try instead:

print(df["country"].apply(lambda x: country_to_continent(x)))