Another solution you can use with np.where:
Just an example DataFrame:
>>> df
Sex
0 male
1 female
2 female
3 female
4 male
Based on the condition create new column new_Sex
>>> df['new_Sex'] = np.where(df['Sex'] == 'male', 0, 1)
>>> df
Sex new_Sex
0 male 0
1 female 1
2 female 1
3 female 1
4 male 0
OR:
>>> df['new_Sex'] = np.where(df['Sex'] != 'male', 1, 0)
>>> df
Sex new_Sex
0 male 0
1 female 1
2 female 1
3 female 1
4 male 0